To mitigate impact to a bumper, and enable the bumper to cope with a kind and the size of container by interposing/inserting an actuator freely telescopic in the lateral direction of a car body in bendable parts of a pair of arms connected to a collision preventive member, and installing the arms on a car body.

A telescopic bumper 9 has a collision preventive member 91, a pair of arms 92, 93 connected to the collision preventive member 91 and bendable in the lateral direction, a fluid pressure actuator 96 freely telescopic in the lateral direction by being interposed/inserted in connecting parts 94, 95 existing in bendable parts of a pair of arms 92, 93, an installing member 97 for installing base end parts of a pair of arms 92, 93 on a frame 98 of an automobile 7 with a container demountable device by a bolt, a nut and a machine screw and a pair of guide members 99 for guiding the collision preventive member 91 in the longitudinal direction of a car body 89. The arms 92, 93 can bend by being respectively connected by the connecting parts 94, 95.