To realize a structure to protect a driver sufficiently by an air bag, regardless of the difference of the physique and the driving posture of the driver.

When a collision accident has happenend, a release lever 17 is rotated by an actuator 20 for release, and the fixation of a supported bracket 11 to a support bracket 9 is released. Under such a condition, a steering column 8 is displaced to the front side, and it makes a necessary interval between an air bag expanded at its steering wheel part, and a driver. And by a regulating means 21 consisting of a stopper 26 and an actuator 27, the displacement amount to the front side of the steering column 8 is regulated, depending on the physique of the driver and the like.