A drive unit includes a main wheel having an annular member, and a plurality of driven rollers that are rotatably attached to the annular member, a plurality of first drive rollers and a plurality of second drive rollers, which are provided with the annular member between them and arranged such that they make contact with the outer peripheral faces of the driven rollers, a first holder and a second holder, which are arranged with the annular shaft between them and respectively hold the plurality of first drive rollers and the plurality of second drive rollers while allowing them to rotate, and a first drive unit and a second drive unit that rotationally drive the first holder and the second holder respectively; grooves are formed in the outer peripheral faces of the driven rollers at an angle to the circumferential direction thereof.