An apparatus and a method for controlling an internal combustion engine, detects a rotating direction of an output shaft of the internal combustion engine. The internal combustion engine includes a crank angle sensor for outputting a pulse signal in accordance with rotation of a crankshaft. The crank angle sensor outputs at the time of reverse rotation of the crankshaft a pulse signal POS having a wider pulse width than that at the time of forward rotation. A control unit receiving pulse signal POS calculates a difference between a present value and a previous value of a pulse width of pulse signal POS and detects switching of a rotating direction of the crankshaft based on a magnitude of this difference. Thus, it is possible to suppress lowering of detection accuracy of a rotating direction of the crankshaft under the influence of variation of measurement values of the pulse width.