To provide a battery charger with suppressed adverse effects due to heat generation of the battery charger.

A battery charger includes: a body case 10 that has a box shape and in which its top surface area is formed larger than the bottom surface of a battery pack BP to be mounted; a mounting part 20 that is provided on the top surface of the body case 10 and is used for mounting the battery pack BP in a standing position; a circuit board 30 that is embedded in the body case 10 and on which a charging circuit 32 supplying power for charging the battery pack BP mounted on the mounting part 20 is mounted; and a cover part 14 that covers the surface of the body case 10 and has heat insulating properties. The inside of the body case 10 is divided into a battery mounting region in which the mounting part 20 is provided and a circuit arrangement region in which the charging circuit 32 is arranged, and the mounting part 20 is provided at a position eccentric to the center of the body case 10.