A steering lock device, comprising: a frame having a lock accommodating hole being a through-hole; a lock member arranged in the lock accommodating hole and configured to shift between a lock position to prevent a rotation of a steering shaft and a lock release position to allow the rotation of the steering shaft; and an auxiliary lock structure configured to prevent a shift of the lock member, wherein the auxiliary lock structure comprises an auxiliary lock member arranged inside the frame and configured to shift between an auxiliary lock position to engage with the lock member and prevent the shift of the lock member and an auxiliary lock release position to allow the shift of the lock member, an auxiliary biasing unit configured to bias the auxiliary lock member from the auxiliary lock release position toward the auxiliary lock position and engage with a spring linkage portion of the auxiliary lock member, and a trigger provided on an inner surface of a cover mounted to the frame, and configured to engage with the auxiliary biasing unit and hold the auxiliary lock member in the auxiliary lock release position, wherein the auxiliary lock member is configured to move to the auxiliary lock position upon falling of the trigger and release of the engagement between the trigger and the auxiliary biasing unit. a frame having a lock accommodating hole being a through-hole; a lock member arranged in the lock accommodating hole and configured to shift between a lock position to prevent a rotation of a steering shaft and a lock release position to allow the rotation of the steering shaft; and an auxiliary lock structure configured to prevent a shift of the lock member, wherein the auxiliary lock structure comprises an auxiliary lock member arranged inside the frame and configured to shift between an auxiliary lock position to engage with the lock member and prevent the shift of the lock member and an auxiliary lock release position to allow the shift of the lock member, an auxiliary biasing unit configured to bias the auxiliary lock member from the auxiliary lock release position toward the auxiliary lock position and engage with a spring linkage portion of the auxiliary lock member, and a trigger provided on an inner surface of a cover mounted to the frame, and configured to engage with the auxiliary biasing unit and hold the auxiliary lock member in the auxiliary lock release position, an auxiliary lock member arranged inside the frame and configured to shift between an auxiliary lock position to engage with the lock member and prevent the shift of the lock member and an auxiliary lock release position to allow the shift of the lock member, an auxiliary biasing unit configured to bias the auxiliary lock member from the auxiliary lock release position toward the auxiliary lock position and engage with a spring linkage portion of the auxiliary lock member, and a trigger provided on an inner surface of a cover mounted to the frame, and configured to engage with the auxiliary biasing unit and hold the auxiliary lock member in the auxiliary lock release position, wherein the auxiliary lock member is configured to move to the auxiliary lock position upon falling of the trigger and release of the engagement between the trigger and the auxiliary biasing unit.