A friction gearing has housing and a unit housed in the housing, the unit including a first roller, a second roller and rotatable support plates. The first roller and the second roller are in frictional engagement with each other under a radial pressing force. The radial pressing force is variable in response to a change in the radial distance between the first and the second roller. The rotatable support plates support the first and the second rollers and receive a resisting force that is generated when the first and the second rollers come in contact under the pressing force. The unit is received in the housing with the axis of rotation of the first roller radially fixed while the first roller is rotatably supported by the housing.