Drive disks are configured to rotate a main wheel by applying a frictional force thereto. Each of the drive disks includes a base and a plurality of rollers. The base includes a first sheet metal member and a second sheet metal member. The first sheet metal member includes a first central part and a plurality of first arm parts. The second sheet metal member includes a second central part and a plurality of second arm parts. Each of the rollers has a first end and a second end in an axial direction thereof. Each of the first arm parts and each of the second arm parts support the first end of one of two rollers adjacent to each other and the second end of the other of the two rollers adjacent to each other.