A drum includes a cylindrical body, a cylindrical head frame, which is fitted to the outer circumference of the body, a hoop located at the outer circumference of a head, lugs located at the outer circumference of the body, lug nuts, and lug bolts. A loosening prevention structure is located between the lower surface of the head of each lug bolt and the upper surface of the hoop. Each loosening prevention structure is formed by a washer with rubber according to a preferred embodiment. The washer with rubber is formed by an annular elastic body and a bowl-shaped cover. The elastic body is made of rubber. The cover includes a cylindrical portion, which covers the outer circumference of the elastic body. The cylindrical portion is formed to be shorter than the elastic body along the axial direction of the body.