A drive mechanism includes a first transmission mechanism that transmits a driving force of a drive unit to a first rotary member to rotate the first rotary member; a second transmission mechanism including a first drive path along which the second transmission mechanism transmits the driving force to a second rotary member through a first gear train to rotate the second rotary member, and a second drive path along which the second transmission mechanism transmits the driving force to the second rotary member through a second gear train to rotate the second rotary member, the second gear train having a gear ratio that differs from a gear ratio of the first gear train; and a switching mechanism that is operated by the driving force and switches the second transmission mechanism between the first drive path and the second drive path.