A clutch unit comprising: a first housing which is provided with a groove recessed inwards; a second housing which is inserted to the groove of the first housing, and is provided with one or more arc portions to protrude along a circumference thereof on one surface thereof; one or more first roller portions which are positioned between the first arc portions; and a first rotation transfer portion which is inserted to the second housing and is rotated in accordance with rotation of a motor, wherein rotation of the first housing is controlled by the first rotation transfer portion and torque is transferred from the motor via the first rotation transfer portion to the first housing when the first housing is engaged to the first roller portions, and the first housing is freely rotatable when the first housing is disengaged from the first roller portions, characterized by further comprising an attachment and detachment module which changes relative rotation speeds of the first housing and the second housing provided with one or more second arc portions on the other surface thereof to fasten and unfasten the first roller portions to and from the first housing, wherein the attachment and detachment module includes: a third housing which is provided with a through-hole in a length direction, one or more second roller portions which are inserted to a through-hole, are positioned between the second arc portions, and are pushed and rotated by the second arc portions in accordance with rotation of the second arc portions, a second rotation transfer portion which is inserted to the through-hole of the third housing and is pushed and rotated in accordance with rotation of the second roller portions, and a motor connection portion which is coupled to one surface of the third housing, is connected to a motor, is rotated in accordance with rotation of the motor, and is provided with a rotation shaft transferring rotational force of the motor to the first rotation transfer portion, wherein the second rotation transfer portion has one area formed of a material having dynamic stability and reduces a rotation speed of the second housing. a first housing which is provided with a groove recessed inwards; a second housing which is inserted to the groove of the first housing, and is provided with one or more arc portions to protrude along a circumference thereof on one surface thereof; one or more first roller portions which are positioned between the first arc portions; and a first rotation transfer portion which is inserted to the second housing and is rotated in accordance with rotation of a motor, wherein rotation of the first housing is controlled by the first rotation transfer portion and torque is transferred from the motor via the first rotation transfer portion to the first housing when the first housing is engaged to the first roller portions, and the first housing is freely rotatable when the first housing is disengaged from the first roller portions, characterized by further comprising an attachment and detachment module which changes relative rotation speeds of the first housing and the second housing provided with one or more second arc portions on the other surface thereof to fasten and unfasten the first roller portions to and from the first housing, wherein the attachment and detachment module includes: a third housing which is provided with a through-hole in a length direction, one or more second roller portions which are inserted to a through-hole, are positioned between the second arc portions, and are pushed and rotated by the second arc portions in accordance with rotation of the second arc portions, a second rotation transfer portion which is inserted to the through-hole of the third housing and is pushed and rotated in accordance with rotation of the second roller portions, and a motor connection portion which is coupled to one surface of the third housing, is connected to a motor, is rotated in accordance with rotation of the motor, and is provided with a rotation shaft transferring rotational force of the motor to the first rotation transfer portion, wherein the second rotation transfer portion has one area formed of a material having dynamic stability and reduces a rotation speed of the second housing. a third housing which is provided with a through-hole in a length direction, one or more second roller portions which are inserted to a through-hole, are positioned between the second arc portions, and are pushed and rotated by the second arc portions in accordance with rotation of the second arc portions, a second rotation transfer portion which is inserted to the through-hole of the third housing and is pushed and rotated in accordance with rotation of the second roller portions, and a motor connection portion which is coupled to one surface of the third housing, is connected to a motor, is rotated in accordance with rotation of the motor, and is provided with a rotation shaft transferring rotational force of the motor to the first rotation transfer portion, wherein the second rotation transfer portion has one area formed of a material having dynamic stability and reduces a rotation speed of the second housing.