In the motor-driven steering lock device 10, cam grooves 50 inclined relative to a circumferential direction of a cylindrical part 46 of a lock bolt 44 are formed on an outer circumferential surface of the cylindrical part 46, a cylindrical rotator 26 that is driven to rotate by an electric motor 16 is provided, the cylindrical part 46 of the lock bolt 44 is disposed inside the rotator 26 so as to be movable in an axial direction of the rotator 26, and cam followers 32 held in longitudinal grooves 30 of the rotator 26 are moved in the cam grooves 50 so as to move the lock bolt 44.