The Ministry of Defence (MoD) is charged with coordinating and supervising all agencies and functions of the government relating directly to national security and the Indian armed forces. The President of India is the ceremonial commander-in-chief of the armed forces of the country. The Ministry of Defence provides policy framework and resources to the armed forces to discharge their responsibility in the context of the defence of the country. The Indian Armed Forces (including Indian Army, Indian Air Force, Indian Navy) and Indian Coast Guard under the Ministry of Defences are primarily responsible for ensuring the territorial integrity of the nation.

At present, the undergoing new creation of National Defence University, for training of military officials and concerned civilian officials, will be administered and overseen by Ministry of Defence. The ministry organises and runs Republic Day celebrations and parade every year in January, hosting a chief guest. The Ministry has the largest budget among the federal departments of India and currently maintains fourth in military expenditure,^[9][10][11] among countries of the world.^[12]

A military department was created by the supreme government of the British East India Company at Kolkata in the year 1776.^[13] Its main function was to co-ordinate and record orders, relating to the army, issued by various departments of the government of the East India Company. The Military Department initially functioned as a branch of the Public Department and maintained a list of army personnel.^[13]

With the Charter Act 1833 the Secretariat of the Government of the East India Company was reorganised into four departments, each headed by a secretary to the Government.^[13] The armies in the presidencies of Bengal, Bombay and Madras functioned as the respective presidency armies until April 1895, when the presidency armies were unified into a single Indian Army. For administrative convenience, it was divided into four commands: Punjab (including the North West Frontier), Bengal (including Burma), Madras and Bombay (including Sind, Quetta and Aden).^[13]

The supreme authority over the Indian Army was vested in the Governor General-in-Council, subject to the control of the Crown, which was exercised by the Secretary of State for India. Two members in the Council were responsible for military affairs. One was the Military Member, who supervised all administrative and financial matters. The other was the commander-in-chief who was responsible for all operational matters.^[13] The Military Department was abolished in March 1906 and was replaced by two separate departments; the Army Department and the Military Supply Department. In April 1909 the Military Supply Department was abolished and its functions were taken over by the Army Department. The Army Department was redesignated as the Defence Department in January 1938. The Department of Defence became the Ministry of Defence under a cabinet minister in August 1947.^[13]

The functions of MoD which in 1947 was mainly logistic support to the armed forces, has undergone far reaching changes. In November 1962, following the 1962 war, a Department of Defence Production was set-up to deal with research, development and production of defence equipment. In November 1965, the Department of Defence Supplies was created for planning and execution of schemes for import substitution of requirements for defence purposes. These two Departments were later merged to form the Department of Defence Production and Supplies.

In 1980, the Department of Defence Research and Development was created. In January 2004, the Department of Defence Production and Supplies was renamed the Department of Defence Production. A Scientific Adviser to the Defence Minister was appointed to advise on scientific aspects of military equipment and the research and design of defence forces equipment. The Department of Ex-Servicemen Welfare was created in 2004.

The Ministry of Defence consists of four Departments; Department of Defence, Department of Defence Production, Department of Defence Research and Development, and Department of Ex-Servicemen Welfare. The Defence Secretary functions as head of the Department of Defence,^[14][15] and is additionally responsible for coordinating the activities of the four Departments in the Ministry.^[14][15]

The principal functions of all the Departments are as follows:

Institute for Defence Studies and Analyses, Defence Institute of Advanced Technology, Defence Institute of Psychological Research and National Defence University come under administration and purview of the Ministry of Defence.

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To ensure a high degree of synergy between the Armed forces, the Government has set up the Integrated Defence Staff, headed by the Chief of Integrated Staff as the Chairman. It was created on 1 October 2001 based on the recommendations of the Group of Ministers which was set up in 2000 (post-Kargil) to review India's defence management.^[19] It acts as the point organisation for integration of policy, doctrine, war fighting and procurement by employing best management practices. The current Chief of Integrated Defence Staff is Lieutenant General PS Rajeshwar, who took over on 1 November, 2018.^[20]

"Chiefs of Staff are the authority for advising the Defence Minister and normally through him the Cabinet Committee on Political Affairs on all military matters which require ministerial consideration". The Integrated Defence Staff is '"the principal arm and Secretariat to the Chiefs of Staff Committee"^[21][22]

The Chiefs of Staff Committee is composed of: (a) Chief of the Army Staff (COAS); (b) Chief of the Naval Staff (CNS); (c) Chief of the Air Staff (CAS); and (d) Chief of Integrated Defence Staff (CIDS) (non-voting member). The Scientific Adviser to the Minister of Defence is invited to attend whenever needed.^[21]

The senior most member of the COSC is appointed its chairperson. General Bipin Rawat is the current head of COSC.^[23]

SIS/TID is a highly classified division within the walls of Ministry of Defence under the Government of India. Very limited information is available for this division.

The responsibility for national defence "rests with the Cabinet, which is discharged through the Ministry of Defence, which provides the policy framework and wherewithal to the Armed Forces to discharge their responsibilities in the context of the defence of the country. The Raksha Mantri (Defence Minister) is the head of the Ministry of Defence."^[13]

The Defence Ministry is responsible for "obtaining policy directions of the Government on all defence and security related matters" and communicating these directions to "Services Headquarters, Inter-Services Organisations, Production Establishments and Research and Development Organisations".^[13] The MoD works closely with the National Security Council, Ministry of External Affairs and the Ministry of Home Affairs.

MoD is headed by the Minister of Defence, who is supported by one, or more than one, minister of state.^[13]

There are about 400,000 defence civilians, under the MOD including Ministry of Finance personnel attached to MOD. In 2015–16 Defence pension bill was ₹54,500 crore (equivalent to ₹590 billion or US$8.5 billion in 2018) of which about 36 per cent was on account of defence civilians.[66]

The ministers are supported by a number of civilian, scientific and military advisers.

The Defence Secretary as head of the Department of Defence,^[14] is the senior most civil servant in the ministry and is responsible for coordinating the activities of the four departments in the ministry.^[14] His or her role is to ensure that the MoD operates effectively as a department of the government.^[24][25][14] Defence Secretary is assisted by additional secretaries and joint secretaries to Government of India posted in the ministry. The Defence Secretary, generally is an officer from the Indian Administrative Service, apart from the Defence Secretary, there are three other secretary-level posts in the Ministry of Defence.

Scientific Adviser to Defence Minister plays a key role in formulation of research and development policies and promoting self-reliance in Indian defence industries.

The Finance Division of the Ministry of Defence is headed by the Financial Adviser (Defence Services). He or she exercises financial control over proposals involving expenditure from the Defence Budget and is responsible for the internal audit and accounting of defence expenditure. In the latter tasks, he or she is assisted by the Controller General of Defence Accounts.

In 1955, the title of Commander-in-Chief was abolished and the three service chiefs were designated as the Chief of the Army Staff, the Chief of the Naval Staff and the Chief of the Air Staff. The heads of the three services of Indian Armed Forces are: