An abnormality detector of a turbocharged engine includes: a compressor including a plurality of blades that are detected portions; and a detecting portion configured to electrically detect the plurality of blades. Each time the blades are detected a predetermined number of times, one pulse having a pulse width corresponding to a measurement time required to detect the blades is output, and a turbo revolution is calculated from the pulse width of the output pulse. When it is judged that a rotation change of the rotating body which change is calculated based on a pulse width of a first pulse and a pulse width of a second pulse output after the first pulse exceeds a predetermined rate in a region where the rotating body exceeds a predetermined revolution, it is determined that an abnormality of the blade or an electromagnetic noise abnormality of the detecting portion occurs.