Supercharger control device for internal combustion engine

A turbocharging system of an internal combustion engine includes compressor of a turbocharger disposed on an intake passage of an internal combustion engine and a turbine disposed on an exhaust passage of the internal combustion engine. A bypass passage connects an upstream side and a downstream side of the turbine in the exhaust passage together. A wastegate valve, which is disposed on the bypass passage, opens and closes the bypass passage according to turbocharging pressure of the compressor. An accumulator, which accumulates exhaust gas pressure, is connected to a downstream side of the wastegate valve in the bypass passage. A recirculation passage connects the accumulator and an upstream side of the turbine together, and a recirculation valve, which opens and closes the recirculation passage based on an output request, is deposed on the recirculation passage.