A camera having a lens barrier movable between an open and a closed position, a lens movable between a photographing position and a non-photographing position and a locking member which, when driven by movement of the lens barrel to the photography position, enters into an opening in the barrier if an attempt is made to move the barrier from the open position towards the closed position. A pressing spring returns the locking member to the withdrawn position when the lens barrel is moved to the non-photographing position. An elastic pressing plate is preferably used to drive the locking member to the projected position against the force of the pressing spring when the lens is moved towards the photographing position.