A steering lock that is easy to assemble but difficult for an automobile thief to dismantle. The steering lock includes a cover on which a support structure for supporting a lock mechanism is integrally formed. The lock mechanism is attached to the cover to assemble a first subunit. A steering lock ECU is attached to an ECU case to assemble a second subunit. The first subunit is attached to the second subunit to assemble a lock unit. The lock unit is attached to the housing. A bolt fastens the lock unit and the housing to each other. A second connector is then attached to the housing.