A drive unit for rotating a first rotary member and a second rotary member disposed around the first rotary member includes a drive source, an output gear driven by the drive source, a first gear greater in diameter than the output gear and configured to engage the output gear, a first joint member projecting from the first gear coaxially and coupled to the first rotary member, a second gear smaller in diameter than the first gear and connected between the first gear and the first joint member, a driven gear smaller in diameter than the first gear and disposed within an area of the first gear in a radial direction thereof to engage the second gear to be driven thereby, and a second joint member projecting from the driven gear coaxially and connected to the second rotary member.