A supercharger can have a lubrication system that includes a speed increasing mechanism, accommodated in a second housing, for increasing the rotation speed of a drive shaft and transmitting the increased rotation speed to a rotary shaft. An oil sump can be configured to for hold lubricant oil for lubricating the speed increasing mechanism. A pump mechanism can be driven by the rotation of the drive shaft to supply the lubricant oil held in the oil sump to the speed increasing mechanism, in which the pump mechanism is constituted with a screw pump made up of a screw provided on the drive shaft. A pump chamber can rotatably support the drive shaft and accommodate the screw. An oil introduction hole and an oil introduction tube can connect the oil sump and the interior of the pump chamber, and a gap can be formed between the screw and the pump chamber.