In 1975, the National Legislative Assembly acting as the National Assembly enacted the Parliamentary Administration Act, B.E. 2518 (1975). According to this act, the subordinate parliamentary agencies are the Secretariat of the National Assembly and parliamentary agencies which may be given other titles. The Secretariat of the National Assembly has functions of carrying out the activities of the National Assembly’s affairs and maintaining order of the National Assembly and its boundary. The Secretariat of the National Assembly is headed by a Secretary-General of the National Assembly who is directly accountable to the President of the National Assembly. In performing his/her functions, the Secretary-General may have Deputy Secretaries-General to assist him/her in carrying out the work of the National Assembly.

    In 1991, a number of laws of parliamentary agencies has been amended by the National Legislative Assembly acting as the National Assembly. In amending of the said laws, the Parliamentary Official Commission considered to amend laws concerning the Secretariat of the National Assembly and Parliamentary Officials to be appropriate and consistent with other kind of officials. Then, the Council of Ministers proposed the Parliamentary Administration Bill (No. ..) B.E. .… and the Parliamentary Official Regulations (No. ..) B.E. …. to the consideration of the National Legislative Assembly and were approved to promulgate as laws.

    The crucial substance of the Parliamentary Administration Act (No.2) B.E. 2535 (1992) and the Parliamentary Official Regulation Act (No.4) B.E. 2535 is as follows:

• To designate the subordinate parliamentary agencies comprising the Secretariat of the Senate, the Secretariat of the House of Representatives and parliamentary agencies which may be given other titles. Each agency has the status of a department and a juristic person. If it is necessary to set up any parliamentary agency which may be given other titles, it must be proceeded through the bill.
• To transfer powers and duties of the Secretariat of the National Assembly including its authorities, enterprises, assets, rights, liabilities, officials, employees and budgets to the Secretariat of the Senate and Secretariat of the House of Representatives. Secretary-General and Deputy Secretaries-General of the National Assembly shall join in the division and determination of workplace.
• Since the National Assembly notification of the division of public agencies of the Secretariat of the Senate comes into force the next day after publication in the Government Gazette, the Secretariat of the Senate is deemed to be established on 12th September B.E. 2535 (1992) [Published in the Government Gazette, Vol.109, Part 93, dated 11th September B.E. 2535 (1992)].