In a frictional drive device comprising a pair of drive disks (48) each rotatably supported by a frame (10) around a central axial line (A) in a mutually opposing relationship and configured to be individually rotatively actuated by a pair of first actuators (45), a plurality of drive rollers (58) arranged along an outer periphery of each drive disk each via a roller bracket (52) which is rotatable around a center line (B) extending in a radial direction at an angle with respect to the central axial line of the drive disks, each roller bracket rotatably supports the corresponding drive roller so as to be rotatable along a prescribed plane of rotation, and an annular main wheel (100) disposed at least approximately coaxially with respect to the central axial line and engaged by the drive rollers of the drive disks, the main wheel comprising an annular member (102) and a plurality of driven rollers (106) supported along the annular member so as to be rotatable around a tangential line of the annular member, each drive roller is configured to be selectively turned around the center line of the corresponding roller bracket. Thereby, the drive efficiency of the frictional drive device can be improved over a wide range of drive mode. When the frictional drive device is incorporated in an inverted pendulum type vehicle as a drive unit (40), the variable arrangement for the drive rollers can be conveniently used for imparting a yaw moment to the vehicle.