A connector comprising: a mating housing including a locked section ; a housing fitted into or detached from the mating housing; and a fitting detection member assembled to the mating housing and movable between a temporary locked position and a regular locked position when the mating housing and the housing are fitted, wherein: the housing includes a member housing section configured to house the fitting detection member , a lock section locked to or detached from a locked section of the mating housing, and a flexible lock arm having locking release sections each of which is configured to slide along an inclined section of the fitting detection member and to release a locked state of the lock section and the locked section , the fitting detection member includes the locked portion locked to or detached from the lock section of the 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 the mating housing and the housing is released, the flexible arm section is bent and deformed in a direction in which a locking margin (S) between the locking protrusion of the member housing section and the slip-off prevention locking section of the flexible arm section increases. a mating housing including a locked section ; a housing fitted into or detached from the mating housing; and a fitting detection member assembled to the mating housing and movable between a temporary locked position and a regular locked position when the mating housing and the housing are fitted, wherein: the housing includes a member housing section configured to house the fitting detection member , a lock section locked to or detached from a locked section of the mating housing, and a flexible lock arm having locking release sections each of which is configured to slide along an inclined section of the fitting detection member and to release a locked state of the lock section and the locked section , the fitting detection member includes the locked portion locked to or detached from the lock section of the 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 the mating housing and the housing is released, the flexible arm section is bent and deformed in a direction in which a locking margin (S) between the locking protrusion of the member housing section and the slip-off prevention locking section of the flexible arm section increases. the housing includes a member housing section configured to house the fitting detection member , a lock section locked to or detached from a locked section of the mating housing, and a flexible lock arm having locking release sections each of which is configured to slide along an inclined section of the fitting detection member and to release a locked state of the lock section and the locked section , the fitting detection member includes the locked portion locked to or detached from the lock section of the 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 the mating housing and the housing is released, the flexible arm section is bent and deformed in a direction in which a locking margin (S) between the locking protrusion of the member housing section and the slip-off prevention locking section of the flexible arm section increases. <EOS>