WHEEL

A wheel (10) of the present invention includes a barrel holder (11), barrel support shafts (12), barrels (13), and bearings (24). The barrel holder (11) is rotationally driven. The barrel support shafts (12) arranged on the circumference of the barrel holder (11) at an angle to a rotation axis of the barrel holder (11). The barrels (13) are barrel-shaped rotating bodies. The barrels (13) are rotatably supported on the corresponding barrel support shafts (12), and outer surfaces of the barrels (13) contact a surface on which the wheel (10) travels as the barrel holder rotates (11). The bearing (24) supports the retainer (24d). A groove (40) is formed at least in a region of the outer circumferential surface of the barrel support shaft (12) extending in the axial direction and including a radially inner projected area of the retainer (24d).