A swing suppressing device includes a damper that may switch over between an expansion/retraction enable condition and an expansion/retraction disable condition; and a link mechanism for coupling the damper and the axle with each other. The damper is disposed with its expansion/retraction direction substantially in a horizontal direction between the vehicle body and the axle, and with its one end being connected to the vehicle body and the other end being connected to the axle through the link mechanism. The link mechanism converts the swing motion in the up-and-down direction of the axle and transmits it to the damper.