To improve vehicle stability in performing loading work and to improve running stability above a predetermined speed while improving riding comfort on a bumpy road.

A steer axle 5 which is a rear axle of a fork lift is swingable in lateral direction about a swing shaft 9. Even when an ignition key 89 is turned on, as long as an operation switch 88 is turned off, an electromagnetic selector valve 83 is not actuated. Accordingly, a connection position to a piping is at a C position, which supplies hydraulic fluid on a hydraulic piping 79 to a driving hydraulic cylinder 31 through a piping 81, the electromagnetic selector valve 83, and a piping 49. A slider 23 abuts against a stopper 19 to restrict a swinging motion of the steer axle 5. When the operation switch 88 is turned on, the electromagnetic selector valve 83 is energized and the connection position comes to a D position. Accordingly, the hydraulic fluid is not supplied to the driving hydraulic cylinder 31. As a result, the slider 23 parts from the stopper 19, allowing the swinging motion of the steer axle 5.