The Government Ministries of Thailand (Thai: กระทรวง: Krasuang) are the government agencies that compose the executive branch of the Government of Thailand. Each ministry is headed by a minister of state (Thai: รัฐมนตรีว่าการกระทรวง, RTGS: Ratthamontri Wa Kan Krasuang) and, depending on the prime minister, several deputy ministers (Thai: รัฐมนตรีช่วยว่าการกระทรวง) . The combined heads of these agencies form the Cabinet of Thailand. There are 19 ministries.[1] The combined employees of these departments make up the civil service of Thailand.
During the Rattanakosin Period, the kingdom's administration was similar to that of the Ayutthaya Period. There were two chief ministers (Thai: อัครมหาเสนาบดี: Akkhramahasenabodi): the first running military affairs or samuhakalahom (Thai: สมุหกลาโหม), and the second Samuhanayok (Thai: สมุหนายก) for civilian affairs. The civilian ministry was divided further into four kroms (Thai: กรม), headed by a senabodi (Thai: เสนาบดี) or 'minister'. This type of administration was called the Chatusadom (Thai: จตุสดมภ์) :
King Chulalongkorn (Rama V), who had received a European education and traveled widely, reformed the administration of the state. In 1875, he issued a royal decree to bring about this reform, dividing and creating many departments, and thereby preventing the archaic system from collapsing.
The administrative reforms of Chulalongkorn created six ministries (Thai: กระทรวง: krasuang), each headed by a minister of state or (Thai: รัฐมนตรี, RTGS: ratthamontri):
A further four were soon added:
By 1900 the entire structure was formed. The ten ministries became the center of Siamese government and rule. After the 1932 Revolution, most of the ministries were retained by the Khana Ratsadon, however from then on the ministers were chosen by the prime minister and not the king.