A steering lock device has a steering catch mechanism including a handlebar attached to a steering stem, and a locking arm attached to this handlebar and being equipped with a lock pin for engagement on the tip end portion thereof. The steering catch mechanism also includes a locking claw as an engaging portion that is engagable with the lock pin. The locking claw is usually biased in the unlocking direction. In this catch mechanism, the locking claw is disposed on a rotation track of the lock pin. Accordingly, when an external force is applied to the lock pin such that the lock pin is in contact with the locking claw of the catch mechanism, the locking claw is moved in the locking direction so that the locking claw can be engaged with the lock pin. Therefore, a steering-lock stand-by state is accomplished.