A control device for a turbocharger with an electric motor includes a turbocharger which is provided along with an internal combustion engine and supercharges air taken in the internal combustion engine using a compressor; an electric motor which can increase a supercharging pressure by running the compressor of the turbocharger; and a controller. The controller calculates a base amount of electric power to be supplied to the electric motor based on a target supercharging pressure and an actual supercharging pressure, decides an amount of electric power to be supplied to the electric motor, controls the electric motor based on the decided amount of electric power to be supplied, and sets the amount of electric power to be supplied to a maximum amount of electric power in a beginning state of an electric power supplied motor, only when the compressor is out of a region where a surge occurs, regardless of the calculated base amount of electric power.