Abstract: A motor unit having a drive motor, a control portion, and a base made of an aluminum die-casting product. The motor unit is fixed to a fixing stand of a sewing machine for driving a drive shaft thereof. The base has a pair of supporting brackets connected to the fixing stand for suspendingly fixing the base to the fixing stand. The base has a plate-like portion. The drive motor is fixed to one surface of the plate-like portion, and the control portion is fixed to an opposite surface thereof. A motor cover made of a synthetic resin is mounted on the one surface for covering the drive motor, and a protection cover made of a synthetic resin is mounted on the opposite surface for covering the control portion. The control portion includes a plurality of electronic components including heat generating elements. The heat generating elements are directly mounted on the base to release heat from the base.