An engine ECU executes a program including the steps of: determining that the condition that there is a possibility of occurrence of knocking is satisfied, based on the result of comparison between a vibration waveform of an engine and a knock waveform model; calculating a 40CA integrated value by integrating magnitudes of vibration occurring in the engine for a range of crank angle of 40°; calculating a knock magnitude N by dividing the 40CA integrated value by a BGL; determining that knocking has occurred when the knock magnitude N is larger than a determination value V(KX); and determining that knocking has not occurred when the knock magnitude N is smaller than the determination value V(KX).