The Ministry of Defence (Abrv: MOD; Thai: กระทรวงกลาโหม, RTGS: Krasuang Kalahom), is a cabinet-level government department of the Kingdom of Thailand. The ministry controls and manages the Royal Thai Armed Forces to maintain national security, territorial integrity, and national Defence. The armed forces of Thailand are composed of three branches: the Royal Thai Army, Royal Thai Navy, and Royal Thai Air Force.

Although the King of Thailand is the Head of the Royal Thai Armed Forces (Thai: จอมทัพไทย), his position is only nominal. The ministry and the forces are administered by an appointed politician, the Minister of Defence, a member of the Cabinet of Thailand.

Initially, the Ministry was called Krom Kalahom (Thai: กรมกลาโหม) and its head was called Samuha Kalahom (Thai: สมุหกลาโหม), and it was charged with the protection of the southern border. It was founded in the Ayutthaya period and was retained throughout the Rattanakosin period. The ministry in its current design was formed in 1887, by the order of King Chulalongkorn, to create a permanent military command. This was a result of the increasing threat posed by Western powers. The ministry was first housed in an old horse-and-elephant stable opposite the Grand Palace. A new European-style building was erected to house it. At first the ministry only commanded the army (founded in 1847), but then it incorporated the navy (founded in 1887), and finally, the air force (founded in 1913).

In 1914, King Vajiravudh determined that the act providing for invoking martial law, first promulgated by his father in 1907, was not consistent with modern laws of war nor convenient for the preservation of the external or internal security of the state, so it was changed to the modern form that, with minor amendments, continues to be in force.

• Minister: Phumtham Wechayachai
  • Deputy Minister: General Natthaphon Narkphanit
    • Permanent Secretary: General Sanitchanok Sangkhachan

• Royal Thai Armed Forces Headquarters
  • Chief of Defence Forces: General Songwit Noonpakdee

• Royal Thai Army
  • Commander-in-Chief: General Pana Claewplodtook
• Royal Thai Navy
  • Commander-in-Chief: Admiral Jirapol Wongwit
• Royal Thai Air Force
  • Commander-in-Chief: Air Chief Marshal Punpakdee Pattanakul

• Office of Minister of Defence
• Office of the Permanent Secretary for Defence
• Royal Thai Armed Forces

• Defence Technology Institute (Public Organisation)
• The War Veterans Department
• Bangkok Dock Company

Thai Department of Defence Budget (million baht)

Organisation	FY2018	FY2019	FY2020
Office of the Permanent Secretary	9,250	10,063	10,300
Headquarters	16,802	17,352	17,900
Defence Technology Organization	1,227	1,240	1,300
Army	107,457	111,377	113,700
Navy	43,835	45,485	47,300
Air Force	39,931	41,609	42,900
Totals	218,503	227,127	233,300

The military augments its budgets through its ownership of golf courses, racetracks, boxing stadia, and radio and television stations.

• Royal Thai Army
• Royal Thai Navy
• Royal Thai Air Force