security guard; loss prevention officer
Refers to a person employed to protect property, maintain safety, or prevent theft, such as in stores, buildings, or events. The term is straightforward and neutral.
The department store's loss prevention officer caught a shoplifter.
Many security guards were stationed at the event venue.
守衛 is a more formal or traditional term for a guard, often at gates or entrances of facilities. 保安員 is a modern, occupational term.
Compound of 保安 (ほあん, 'security, safety') and 員 (いん, 'member, personnel'). The word is a straightforward modern occupational term.