A method of controlling a supercharger includes: an information conversion step, a map deducing step, a boost amount deducing step, and a RPM deducing step. In the information conversion step, a sensor detects information of a vehicle, and a control unit converts the information into a factor and saves. The map deducing step includes deducing a total boost amount for driving an engine, and deducing a map for a target boost amount of a supercharger using a boost pressure of a turbocharger. A correction value deduced in the boost amount deducing step is calculated according to vehicle environment information, and a target RPM of the supercharger is calculated based on the target boost amount of the supercharger, and a boost pressure by the supercharger. In particular, the target boost amount of the supercharger is deduced based on the correction value, the converted factor, and the deduced map.