A power-tool battery pack usable as a power supply of a power tool and capable of slidably attaching to and detaching from a tool main body of the power tool includes a battery main body and a case that houses the battery main body. The battery main body includes a female terminal having inner sides configured to electrically connect to and sandwich a male terminal slidably attachable to the battery pack. The case includes a case main body and a case-cover part. The case-cover part has an opening for receiving the male terminal and sandwiching-wall parts for sandwiching the female terminal from outer sides of the female terminal. The female terminal and the sandwiching-wall parts are configured such that, at least when the female terminal sandwiches the male terminal, parts of the female terminal facing the sandwiching-wall parts are caused to touch the sandwiching-wall parts.