To provide a movable bumper which reduces a burden of a worker and enhances operability.

A manual fixture is fixed to a bumper arm 32, can select states fixed to and released from two fixing holes on a base body 21 side by advancing or retracting a piston by a manual operation with respect to a cylinder, can take a state of fixing the bumper arm 32 to a projecting position and a retracting position by fitting the tip of a piston to the fixing hole and a position selecting state of making the bumper arm 32 freely turnable by accommodating the tip of the piston in the cylinder and releasing the fitting to two fixing holes, and keeps an auxiliary spring 39 between the base body 21 and bumper arm 32.