noun
store detective; security officer
Refers to a person responsible for security, especially in a store or commercial facility. Often used for plainclothes loss-prevention staff.
あのデパートの保安係は万引きを見つけるのが上手だ。
The store detective at that department store is good at catching shoplifters.
彼はショッピングモールの保安係として働いている。
He works as a security officer at a shopping mall.
警備員 is a more general term for a security guard, often uniformed and stationed at building entrances or events. 保安係 specifically implies a store detective or in-house security role, often focused on theft prevention.
Compound of 保安 (ほあん, 'security, safety') and 係 (がかり, 'person in charge').