The invention discloses a centrifugal supercharger and a supercharging system for engine using the same. The centrifugal supercharger includes, a drive pulley connected to receive rotating power from an engine. an electronic blocking the rotating power to be supplied to the drive pulley or supplying the rotating power to the drive pulley. a speed increasing device increasing rotation speed of the drive pulley. a compressor including an impeller receiving rotation power having speed increased by the speed increasing device and flowing and compressing external air and an impeller housing.