A drive transmission apparatus includes a sun gear driven by a drive source, a planetary gear, a supporting member that supports the planetary gear capable of revolving around the sun gear in a rotatably engaged state with the sun gear, a driven gear that is engaged with the planetary gear when the planetary gear revolves and moves to an engagement position by the rotation of the sun gear in a first direction, and a rotational force providing unit that provides a rotational force to the driven gear to rotate the sun gear in a second direction opposite to the first direction via the planetary gear when the planetary gear is engaged with the driven gear. When the sun gear is rotated in the second direction by the drive source, the rotational force providing unit blocks the revolution of the planetary gear by rotating the planetary gear via the driven gear.