A connector includes a housing fitted into or detached from a mating housing, and a fitting detection member assembled to a member housing section of the housing and detecting a fitting completion. The fitting detection member includes a locked portion locked to or detached from a lock section of a flexible lock arm, and a flexible arm section provided with a slip-off prevention locking section locked to or detached from a locking protrusion of the member housing section, and when fitting of both the housings is released, the flexible arm section is bent and deformed in a direction in which a locking margin between the locking protrusion of the member housing section and the slip-off prevention locking section of the flexible arm section increases.