INTERNAL COMBUSTION ENGINE MISFIRE DETECTING DEVICE AND MISFIRE DETECTING METHOD

This misfire detecting device for an internal combustion engine having a plurality of cylinders, for detecting a misfire of the internal combustion engine, is provided with: a pulsation component acquiring unit for performing a frequency analysis of operating parameter data indicating a change over time in an operating parameter correlated with an overall operating state of the plurality of cylinders, and for acquiring a pulsation component spectrum, which is a frequency spectrum of pulsations of the internal combustion engine; a difference parameter acquiring unit for acquiring a difference parameter correlated with a degree of difference between the operations of each of the plurality of cylinders; and all-cylinder misfire determining unit for determining that an all-cylinder misfire has occurred in the internal combustion engine if the pulsation component spectrum acquired by the pulsation component acquiring unit falls below a first threshold and the difference parameter acquired by the difference parameter acquiring unit 12 falls below a second threshold.