Engine control apparatus

A crank sensor (15) outputs a crank signal including an angle indicating part and a reference position indicating part. A cam sensor (25) outputs a cam signal including an angle indicating part and a reference position indicating part. A microcomputer (31) executes a cylinder determining processing using the crank signal alone, and also executes a cylinder determining processing using the cam signal alone. In addition, the microcomputer (31) detects abnormality of the crank signal and the cam signal. The cylinder determining processing using the crank signal alone is prohibited when both the crank signal and the cam signal become abnormal while operating the engine. Then, the prohibition of the cylinder determining processing is withdrawn on the condition that the cam signal is recovered to normal.