Abstract: Disclosed is an electric motor system for automobiles having an electric motor and a control circuit for the motor, wherein the control circuit is attached to a part of a metallic housing of the motor system by means of a bonding agent and is embedded in resin material so as to maintain a favorable heat removal from the control circuit by virtue of a high heat conductivity and a heat radiation capability of the housing. Preferably, the housing accommodates a speed reduction unit which is connected to the output shaft of the motor and reduces its rotation speed. Favorable heat removal from the control circuit improves the reliability and the performance of the control circuit, and since the control circuit can be directly wired to the motor the number and the cross section of the electric wires which extend between various parts of the motor system can be reduced.