PURPOSE: To positively regulate the oscillation of a front wheel by winding a wire by the rotation of a drum to pull up a catch guide member, and making a guide pin guide a Y-shape part in the engaged state at the time of releasing the lock of a handle stem, locked by a hook, to fold the handle post around a hinge as a fulcrum.

CONSTITUTION: In the state of the hook 8 of the upper head locking member 6a of a handle stem 5 being engaged with a lower head locking member 6b, a wire 11 is rewound from a drum 22, and a catch guide member 10 is placed in a lower position by a spring 14 so as to make a front fork 2 rotatable. When the engagement of the hook 8 is released, the handle stem 5 becomes foldable around a hinge 7 as a fulcrum; and when this handle stem 5 is folded, the drum 2 is rotated to wind the wire 11. The catch guide member 10 is thereby pulled up, a Y-shape part is guided by a guide pin 23, and the guide pin 23 is restricted by the root of the Y-shape part so as to position the direction of a front wheel.