The head of a prison; a formal title for the person in charge of a correctional facility.
The prison warden met with the new inmate.
刑務官 is a prison officer or guard, a subordinate position to the 刑務所長.
所長 is a general term for the head of any facility or institute; 刑務所長 specifies the head of a prison.
Compound of 刑務所 (prison) and 長 (head, chief).