PURPOSE: To carry out highly stable and reliable control by providing a plurality of pulses in a crank angle reference signal to the ignition cycle of each cylinder and changing over a control reference position according to a timing control region to set the control reference position in a practical control region irrespective of the maximum control position of an internal combustion engine.

CONSTITUTION: When a rotary disc 2 of a rotary signal generator 8 is rotated in the direction of arrow, a crank angle reference signal L1 consisting of pulse rows is obtained on the basis of windows 3a1, 3a2. The crank angle reference signal L1 has the first and second pulses P1 and P2 in each ignition cycle of each cylinder and as a whole the number of pulses two times that of cylinders. On the other hand, a cylinder discriminating signal L2 based on the window 3b is generated to have the phase discrepant from the first pulse P1 of a specified cylinder. A microcomputer 10 discriminates the first pulse P1 while discriminating the specified cylinder on the base of a cylinder discriminating signal L2, and discriminates four reference positions B110°, B75°, B40°, and B5° in each cylinder on the basis of the crank angle reference signal L1 to control respective movement timing. That is, a control reference position is changed over according to a plurality of timing control regions.