A steering lock device includes a motor configured to rotate a motor shaft, a worm attached to the motor shaft of the motor, a main gear configured to rotate along with rotation of the worm, a cam member integrally provided with the main gear, and a rod including an insertion and extraction portion. The insertion and extraction portion is configured to be inserted into and extracted from an opening provided on a steering shaft side in accordance with an operation of the cam member along with rotation of the main gear. At least a part of at least one member of the worm and the insertion and extraction portion is configured to be accommodated in a circumferential region of the main gear when the main gear is viewed in a plan view along a rotation axis direction of the main gear.