An electric power steering apparatus comprising: an electric motor that produces assist torque, based on steering torque produced by a driver of a vehicle; a control unit that controls the electric motor; and a power-source connector that is connected with a battery mounted in the vehicle and supplies respective power sources to the control unit and the electric motor, wherein the electric motor is provided with two sets of armature windings including a first armature winding and a second armature winding that are formed in substantially the same manner, wherein the control unit is formed of two sets of control units that are formed in substantially the same manner and that include a first control unit formed in such a way as to be capable of independently controlling the first armature winding and a second control unit formed in such a way as to be capable of independently controlling the second armature winding, wherein each of the first control unit and the second control unit has a power source relay (5a, 5b) formed in such a way as to be capable of turning on/off a power source, a filter circuit (6a, 6b) connected with the power source relay (5a, 5b), an input circuit (12a, 12b) to which information from a sensor is inputted, a driving circuit (11a, 11b) that generates a driving signal for driving the electric motor, an inverter circuit (3a, 3b) that is controlled by the driving signal, and a control circuit unit (4a, 4b) provided with a CPU (10a, 10b) that outputs to the driving circuit (11a, 11b) a command signal for controlling the electric motor based on the information inputted to the input circuit (12a, 12b), characterized in that the power-source connector is formed of a single connector, wherein out of terminals of the power-source connector, a power source system to be connected at least with the positive-polarity side of the battery branches into two lines in the immediate vicinity of the terminals; one of the branch lines is connected with the first control unit and the other one of the branch lines is connected with the second control unit, wherein each of the two branch lines further re-branches into two lines, wherein the power source relay (5a, 5b), the filter circuit (6a, 6b), and the inverter circuit (3a, 3b) are connected with one of the re-branch lines, and wherein the control circuit unit (4a, 4b) is connected with the other one of the re-branch lines by way of a first detection circuit (36a, 37a) that detects an abnormality in a circuit connected with the control circuit unit (4a, 4b). an electric motor that produces assist torque, based on steering torque produced by a driver of a vehicle; a control unit that controls the electric motor; and a power-source connector that is connected with a battery mounted in the vehicle and supplies respective power sources to the control unit and the electric motor, wherein the electric motor is provided with two sets of armature windings including a first armature winding and a second armature winding that are formed in substantially the same manner, wherein the control unit is formed of two sets of control units that are formed in substantially the same manner and that include a first control unit formed in such a way as to be capable of independently controlling the first armature winding and a second control unit formed in such a way as to be capable of independently controlling the second armature winding, wherein each of the first control unit and the second control unit has a power source relay (5a, 5b) formed in such a way as to be capable of turning on/off a power source, a filter circuit (6a, 6b) connected with the power source relay (5a, 5b), an input circuit (12a, 12b) to which information from a sensor is inputted, a driving circuit (11a, 11b) that generates a driving signal for driving the electric motor, an inverter circuit (3a, 3b) that is controlled by the driving signal, and a control circuit unit (4a, 4b) provided with a CPU (10a, 10b) that outputs to the driving circuit (11a, 11b) a command signal for controlling the electric motor based on the information inputted to the input circuit (12a, 12b), a power source relay (5a, 5b) formed in such a way as to be capable of turning on/off a power source, a filter circuit (6a, 6b) connected with the power source relay (5a, 5b), an input circuit (12a, 12b) to which information from a sensor is inputted, a driving circuit (11a, 11b) that generates a driving signal for driving the electric motor, an inverter circuit (3a, 3b) that is controlled by the driving signal, and a control circuit unit (4a, 4b) provided with a CPU (10a, 10b) that outputs to the driving circuit (11a, 11b) a command signal for controlling the electric motor based on the information inputted to the input circuit (12a, 12b), characterized in that the power-source connector is formed of a single connector, wherein out of terminals of the power-source connector, a power source system to be connected at least with the positive-polarity side of the battery branches into two lines in the immediate vicinity of the terminals; one of the branch lines is connected with the first control unit and the other one of the branch lines is connected with the second control unit, wherein each of the two branch lines further re-branches into two lines, wherein the power source relay (5a, 5b), the filter circuit (6a, 6b), and the inverter circuit (3a, 3b) are connected with one of the re-branch lines, and wherein the control circuit unit (4a, 4b) is connected with the other one of the re-branch lines by way of a first detection circuit (36a, 37a) that detects an abnormality in a circuit connected with the control circuit unit (4a, 4b).