A baseball or softball bat improved in repulsiveness while maintaining sufficient durability is obtained. The bat is a baseball or softball bat including a hitting portion, a tapered portion and a grip portion, and the hitting portion offers a hitting portion core as a core, an elastic body and an outer shell member. The elastic body is arranged on the outer periphery of the hitting portion core. The outer shell member is arranged on the outer periphery of the elastic body. The outer shell member includes outer shell member portions which are a plurality of portions elastically deformable independently of each other.