Abstract: A cassette-type power unit for a motor toy is disclosed, which comprises a rectangular casing provided at its middle part with a partition; connecting terminals for connecting a plurality of batteries in series; contact pieces provided as power terminals on an outer face of the casing; and holding pieces each provided with a flange for serving as a guide and a stopper upon connection to the motor toy.The cassette-type power unit allows the convenient replacement of batteries, especially for a wireless controllable toy car, and enables a variety of controlling operations to be readily effected by use of a single unit.