A driving device comprising: a motor for generating a rotation drive force; a drive gear capable of rotating in a first direction and in a second direction according to forward and reverse rotations of the motor; a swing gear that is disposed to engage with the drive gear and is capable of swinging between a first position and a second position by a rotation drive force transmitted from the drive gear; a first gear member that engages with the swing gear when the drive gear rotates in the first direction so that the swing gear swings to the first position; a second gear member that engages with the swing gear when the drive gear rotates in the second direction so that the swing gear swings to the second position; a frame for holding the first gear member and the second gear member in a rotatable manner; and a bracket having a slide hole for holding a rotation shaft of the swing gear in a slidable and rotatable manner so as to guide the swing gear to the first position and to the second position, the bracket being attached to the frame whereby the slide hole includes a pair of contact parts (111c, 111d) having an arc shape with which the rotation shaft contacts when the swing gear is positioned at the first position and at the second position, characterized by an arc hole part for connecting the pair of contact parts (111c, 111d) with a first sliding surface farther from the drive gear and a second sliding surface nearer to the drive gear, and the first sliding surface has a shape retracting to the opposite side to the rotation shaft from tangential lines (L1, L2) of the rotation shaft contacting with the contact parts (111c, 111d), which are parallel to pressure angle directions between the drive gear and the swing gear, or a shape coinciding with the tangential lines (L1, L2). a motor for generating a rotation drive force; a drive gear capable of rotating in a first direction and in a second direction according to forward and reverse rotations of the motor; a swing gear that is disposed to engage with the drive gear and is capable of swinging between a first position and a second position by a rotation drive force transmitted from the drive gear; a first gear member that engages with the swing gear when the drive gear rotates in the first direction so that the swing gear swings to the first position; a second gear member that engages with the swing gear when the drive gear rotates in the second direction so that the swing gear swings to the second position; a frame for holding the first gear member and the second gear member in a rotatable manner; and a bracket having a slide hole for holding a rotation shaft of the swing gear in a slidable and rotatable manner so as to guide the swing gear to the first position and to the second position, the bracket being attached to the frame whereby the slide hole includes a pair of contact parts (111c, 111d) having an arc shape with which the rotation shaft contacts when the swing gear is positioned at the first position and at the second position, characterized by an arc hole part for connecting the pair of contact parts (111c, 111d) with a first sliding surface farther from the drive gear and a second sliding surface nearer to the drive gear, and the first sliding surface has a shape retracting to the opposite side to the rotation shaft from tangential lines (L1, L2) of the rotation shaft contacting with the contact parts (111c, 111d), which are parallel to pressure angle directions between the drive gear and the swing gear, or a shape coinciding with the tangential lines (L1, L2).