An engine control apparatus includes a valve operating mechanism for transmitting the rotation of a crankshaft to camshafts through a timing wrapping member. A control unit includes a phase detection section that detects the phase of a camshaft relative to the crankshaft, an abnormality determination section that makes, based on the detected phase, a determination whether the valve operating mechanism is abnormal, a threshold storage section that stores determination references as a lower limit threshold and an upper limit threshold, an initial phase storage section that stores, as an initial phase, a phase detected at the time of engine installation, and a phase correction section that corrects the phase detected during engine operation by using the initial phase thereby to calculate a corrected phase. The abnormality determination section outputs an abnormality determination signal when the corrected phase deviates from a determination reference range of from the lower to upper limit thresholds.