Abstract: In an engine 1 equipped with a supercharger 40 consisting of a compressor 41 having a plurality of blades 45 on a turbine shaft 42 and a turbine 42, at least one index means 44 is provided on the turbine shaft 42 or the plurality of blades 45, and a turbo angular velocity sensor 62, which detects a rotation of the index means 44 and a rotation of the plurality of blades 45 respectively, is provided and connected to an ECU 60. In the engine 1, also, a turbo angular velocity computing means, which calculates an angular velocity by obtaining a plurality of pulses per one rotation of the turbine shaft, is provided.