According to the present invention, a core member hardly falls off from a lateral plate for protecting an end surface of a roll, and abrasion dust is less likely to be generated. The core member having a length L3 is passed through four rolls each of which is obtained by winding a separator on a core and has a width L1 and five buffering materials each of which has a thickness L2, a protruding section which is included in a protector and has a height L4 is inserted into the core member, and L4>4L1+5L2−L3>0 holds true.