Abstract: A portable power supply has a body case, an attaching portion, an input portion, a voltage lowering portion, a storage battery, an output portion and heat radiating means. The body case has two opposing major surfaces and two sections divided by a prescribed reference line. The attaching portion is provided on one of the major surfaces for detachably attaching the power supply to a human body. The input portion and the output portion are positioned in one of the sections to be exposed from the body case. The input portion is connected to a commercial power source, and the output portion is connected to a prescribed electronic device. The voltage lowering portion lowers power from the input portion. The storage battery is charged by the output from the voltage lowering portion. The heating radiating means is provided on the other one of the major surfaces of the body case and makes the heat radiation of the other one of the major surfaces higher than that of the one of the major surfaces.