The principal staff officer, abbreviated as PSO, is the head of the Armed Forces Division, a ministry level joint forces headquarters under Chief Adviser's office.

It acts as the high command of the national armed forces.

It is currently held by a three-star rank lieutenant general.

He is assisted by a PS (acting PSO) and five departmental heads each one star rank military officer from Bangladesh Armed Forces.

He also, as per government notification, performs the duties of a full-fledged secretary with full administrative and financial authority as that of a secretary in any other division or ministry.