PURPOSE: To prevent a wheel from slipping off due to wheel load as well as to make improvements in riding quality by installing an axle box guard member in a part of an underframe, also installing an axle box being installed in this box free of slide motion, and interposing a stopper member and an elastic body being lengthened in comparison with this stopper, and what is more, low in rigidity both between the axle box and the underframe, then holding this underframe elastically.

CONSTITUTION: Each axle box guard member 3 is hangingly installed in front and rear parts 2a of an underframe 2, and a stopper 4 is installed therein so as to prevent an axle box 8 from slipping off. A stopper member 12 and an elastic body 13 are interposed between an upper spring seat plate 11 and a lower spring seat plate 10. Especially, the elastic body 13 is formed into being longer than the stopper member 12, and it is made up of elasticity being low in rigidity as compared with this stopper member 12, and further it is within the range of a cant's run-off rate. When a linear motor is energized with a continuous rating current, even if there is produced large attraction, an air gap can be stably formed by the elastic body 13, whilesince the stopper member 12 shorter than length of the elastic body 13 is interposingly installed there, any wheel load slip-off is thus preventable.