An electric lock device including a movable member, a cam plate (5) rotated in an unlocking direction and a locking direction by the driving of a drive source, and a lock member (8) including a cam contact surface (10) in contact with a sliding surface (6) of the cam plate (5). The lock member (8) follows the sliding surface (6) to be displaced between a locking position for inhibiting the movement of the movable member and an unlocking position for allowing the movement of the movable member. The cam profile of the sliding surface (6) is set so that the rotary torque of the cam plate (5) necessary for moving the lock member (8) from the locking position to the unlocking position can be maintained at approximately a constant value.