To provide a cogeneration system for efficiently generating electric power both on power demand and on heat demand.

The cogeneration system 10 can supply electric power to a power load 21 in systematic linkage with a commercial power system 20 and also supply heat energy to a heat load 23. It comprises a control means 7 for receiving a specific electric equipment starting signal SIH which is transmitted from the commercial power system 20 on starting specific electric equipment 22 installed for supplying electric power, to start the actuation. Herein, the specific electric equipment 22 is, for example, electric equipment which features the utilization form of the specific electric equipment 22 such as an electromagnetic range for increasing heat demand such as hot water supply demand at least after starting the use.