A connector is provided with a highly reliable lock arm. The connector includes a slider (20) formed to move between a displacement permitting position to a forcible displacement position. The slider (20) and a lock arm (17) are provided with pushing portions (24) and a pushable portion (18), respectively. When the slider (20) is moved from the displacement permitting position to the forcible displacement position with connector housings (10, 40) fitted with each other, slanted surfaces (24A) of the pushing portions (24) push a slanted surface (18A) of the pushable portion (18) to forcibly displace the lock arm (17) to an unlocking position. Since it is not necessary to provide a locking portion of the lock arm (17) and the female connector housing (40) with an unlocking function, reliability of a locking function by the lock (17) can be improved.