A traction-drive type driving-force transmission mechanism includes an output shaft and a sun roller that is rotatable about a first central axis. Shafts having respective second central axes are disposed respectively on corresponding secondary axes, of which is inclined relative to the first central axis in such a manner that each second central axis is aligned with the corresponding secondary axis. A pressing member is coupled to the output shaft. A plurality of speed-reduction rollers are disposed along an outer peripheral surface of the sun roller and are supported by the respective shafts. The pressing member presses each of the speed-reduction rollers against the outer peripheral surface of the sun roller to allow a driving force to be transmitted by a traction force between the sun roller and the speed-reduction roller.