Provided is a cogeneration system. The system includes a chassis, a controller cooling unit, and a driver cooling unit. The chassis is provided with a generator, a driving source, a waste heat recovering unit, and a controller. The generator generates power. The driving source drives the generator and generates heat. The waste heat recovering unit recovers a waste heat of the driving source. The controller controls operations of the generator, the driving source, and the waste heat recovering unit. The controller cooling unit introduces air at one side inside the chassis, circulates the introduced air, and cools at least any one of the generator and the controller. The driver cooling unit introduces air at the other side inside the chassis, circulates the introduced air, and cools at least any one of the driving source and the waste heat recovering unit.