In an engine cogeneration system in which power generators 5 to 8 are driven by a plurality of engines 1 to 4 to thereby supply electric power to power load 22 of a general household, at the same time, heat produced by cooling each of the engines 1 to 4 and heat generated from the exhaust gas are recovered by heat exchangers 18 and 19 to be stored as hot water into a hot-water tank 20 to supply heat to heat load 21 of the general household, the amount of power to be supplied and of the amount of heat to be supplied are controlled by a number of the engines 1 to 4 and the combustion modes of these engines 1 to 4. This engine cogeneration system can follow both the head demand and power demand in a high efficiency.