An ECU includes plural sensor units and plural control units. The sensor units include magnetic field detection elements for detecting a rotation of a motor, and output mechanical angles related to the rotation angle in one rotation and count values related to the number of rotations of the motor, respectively. One rotation of the motor is divided into indefinite regions, in which detection deviation of the count values may occur, and definite regions, in which no detection deviation occurs. The definite region of the count value is set to deviate from the definite region of the other count value. Absolute angle calculation units calculate the absolute angles using the count values of the definite regions.