A belt loop sewing apparatus comprising: a holding unit configured to hold one of ends in a longitudinal direction of a belt loop disposed in the longitudinal direction; a clamp unit including a loop clamp capable of clamping or releasing the other end of the belt loop from a holding position set by the holding unit, the clamp unit configured to move the loop clamp in a direction crossing the longitudinal direction; a fork unit including, on a tip, a fork formed into a forked shape and interposing the belt loop provided between the holding unit and the loop clamp, the fork unit configured to be rotatable around an axis in the direction crossing the longitudinal direction and movable in the direction crossing the longitudinal direction together with the loop clamp to fold one of the ends of the belt loop back toward a central side of the belt loop by a rotation of the fork unit; and a controller configured to control the rotation of the fork unit to fold the one of the ends of the belt loop back toward the central side of the belt loop, wherein the controller is configured to move the loop clamp holding the belt loop in the direction crossing the longitudinal direction to place the belt loop in a sewing position of a sewing machine, and wherein the controller is configured to move the loop clamp holding the belt loop by a predetermined amount in the direction crossing the longitudinal direction and then to rotate the fork unit to fold the end of the belt loop, characterized in that the controller is configured to set a moving direction of the loop clamp to be the direction crossing the longitudinal direction and a direction cancelling the protrusion when one of the ends of the belt loop folded back toward the central side of the belt loop is protruded from the belt loop. a holding unit configured to hold one of ends in a longitudinal direction of a belt loop disposed in the longitudinal direction; a clamp unit including a loop clamp capable of clamping or releasing the other end of the belt loop from a holding position set by the holding unit, the clamp unit configured to move the loop clamp in a direction crossing the longitudinal direction; a fork unit including, on a tip, a fork formed into a forked shape and interposing the belt loop provided between the holding unit and the loop clamp, the fork unit configured to be rotatable around an axis in the direction crossing the longitudinal direction and movable in the direction crossing the longitudinal direction together with the loop clamp to fold one of the ends of the belt loop back toward a central side of the belt loop by a rotation of the fork unit; and a controller configured to control the rotation of the fork unit to fold the one of the ends of the belt loop back toward the central side of the belt loop, wherein the controller is configured to move the loop clamp holding the belt loop in the direction crossing the longitudinal direction to place the belt loop in a sewing position of a sewing machine, and wherein the controller is configured to move the loop clamp holding the belt loop by a predetermined amount in the direction crossing the longitudinal direction and then to rotate the fork unit to fold the end of the belt loop,