In order to improve the performance of centrifugal compressors automotive turbochargers, it is important to understand how the air flows in them. In particular, the flow is very complicated in the rotating impeller of the centrifugal compressor, because of the Coriolis force and the viscous effect. Therefore, a detailed flow measurement of an impeller was carried out using a Laser Doppler Velocimeter (LDV). The test impeller is a scale model of a real turbocharger enlarged 9.1 times. As a result, it was found that a three dimensionally distorted flow existed at a low flow rate, and the low velocity region was grown up at the suction surface of the inducer. The experimental data compared with the three-dimensional viscous flow analysis and an acceptable agreement was observed. Using these measurement results, we have been developing higher performance turbochargers.