PURPOSE: To simplify the constitution and reduce the cost and enhance the reliability by installing N×M pieces of transformers for ignition which are driven in N (N≥2) pieces in each by each ignition signal and installing 2N×M pieces of spark plugs connected in two pieces in each.

CONSTITUTION: An internal combustion engine is equipped with 2M pieces of cylinders #1-#4 in which two pieces in each in opposed cycle are ignited simultaneously. In this case, a standard position signal and a cylinder discrimination signal are generated by a crank angle sensor 1A, and a variety of operation states are detected by a variety of sensors 2, and M pieces of ignition signals are generated by a control means 3A on the basis of the signals. Further, N×M pieces of transistors 43-46 for ignition are driven in N (N≥2)pieces in each by the ignition signal. Further, 2N×M pieces of spark plugs 71a, 71b-74a, and 74b are connected in two pieces in each with each transformer for ignition. Two cylinders in each are simultaneously ignited by N pieces of transformers for ignition, and each electric discharge polarity of N pieces of spark plugs can be carried out complementarily.