A method for detachably attaching a linking unit, including an end with a hole and a slit, to a mold, the method comprising inserting a first attachment member connected to the mold through the hole; and inserting a second attachment member connected to the mold through the slit, wherein the linking unit is detached from the mold by moving the linking unit in a direction opposite to a direction in which the slit is formed in a state where the first attachment member is disconnected from the mold and the second attachment member remains connected to the mold.