PURPOSE: To facilitate an operation for converting direction by providing a caster of the rotary center in the central part of a bed.

CONSTITUTION: A caster 3 at the one end side of a base frame 2 is provided with an operating pedal 4 and the respective casters 3 are interconnected through a pivotable shaft 5 of the operating pedal 4. The casters 3 at the other end side are also interconnected through an interlocking shaft 6 and these pivotable shaft 5 and interlocking shaft 5 are interconnected through an interlocking lever 7. Also, a shaft 8 is provided to cross the interlocking lever 7 in the central part of a base frame 2, and a steering caster 9 is mounted to the shaft member 8 so that the shaft member 8 and interlocking lever 7 are interconnected through the pivotable arm 10 and interconnecting arm 11. Thus, since the steering caster contacts a floor surface to steer a bed or the like while the caster is related, the handling of the bed is substantially facilitated.