To increase a degree of freedom of an installation place by providing a supporting shaft of a drive wheel so as to be rotatable for a base, providing a revolving guide rod in front of the drive wheel on the lower part of a conveyor base and fitting the revolving guide rod so as to be movable within a guide groove.

A drive wheel part 5 is constituted of a pinion 51 to be a drive wheel and a driving source 52 for revolving and driving the pinion 51. On the lower part of a base 2, a revolving guide rod 6 is provided at almost a center part in front of the pinion 51 to be the drive wheel. A tip part of the revolving guide rod 6 is made a swivellable rotary wheel 61. A linear track 7 and a revolving guiding guide 8 are installed on the ground. One side surface of the linear track 7 is made a rack part, the pinion 51 of the drive wheel part 5 is engaged with the rack part and the pinion 51 travels on the linear track by revolving and driving. The revolving guiding guide 8 is constituted of a U-shaped body having a grooved guiding part. The swivellable rotary wheel 61 at the tip part of the revolving guiding rod 6 is fitted into the grooved guiding part.