To allow the regulation of the mass and inertia moment of a bat to a range where the regulation is not possible with the conventional bat mounted with a weight only at the front end or the grip end.

This bat consists of front end parts 3, a barrel 2 and grip end parts 4B and both of the front end parts 3 and grip end parts 4 of the bat are formed as a replacement type. Mass bodies 7 are mounted at the front end parts 3 and/or the grip end parts 4.