Disclosed is an electric power steering apparatus having an electronic control device for controlling motor current based on electric signals inputted from a torque sensor of an automobile and a motor for generating steering power. The electronic control device includes a PCB; a metal substrate formed on a lower side of the PCB in a plate shape while being perpendicular to the PCB; a heating device having a terminal coupled to the PCB and a body coupled to a front surface of the metal substrate; and a radiation plate spaced a predetermined distance from the PCB and having a coupling unit formed on an upper surface of the radiation plate, the metal substrate being coupled to the coupling unit. The body of the heating device is coupled to the metal substrate, which is perpendicular to the PCB, and the metal substrate is coupled to the coupling unit on the upper surface of the radiation plate for improved radiation function.