The Jabatan Adat Istiadat Negara (abbrev: JAIN) is a government department under the Prime Minister's Office that functions to guarantee the constant maintenance of Royal Customs.

[6] On 1 July 1954,[7] the Jabatan Adat Istiadat, Ugama dan Kebajikan Masyarakat (Department of Customs, Religious and Social Welfare) was founded.

With the consent of Sultan Omar Ali Saifuddien III, the department was established by appointing Pengiran Anak Haji Mohamed Alam as the Pegawai Adat Istiadat, Ugama, and Kebajikan Masyarakat (Customs, Religious, and Social Welfare Officer).

[14] The following are the roles and duties of JAIN:[15] The title of Chief (Yang Di-Pertua) of Adat Istiadat Negara was formally elevated to ministerial level on 6 May 2024.

[19] Meetings of the Adat Istiadat Council are usually held at the Bilik Mesyuarat West Wing of the Prime Minister's Office Building.