A hydrogen engine system comprises an engine, a metal hydride container connected with the engine and providing the engine with hydrogen, a heat intermedium providing mechanism connected with the hydrogen occluding alloy container and providing the metal hydride container with heat intermedium, a first control mechanism connected with the heat intermedium providing mechanism and controlling the heat intermedium providing mechanism so that the temperature of the heat intermedium supplied to the metal hydride container be kept at a constant value, and a second control mechanism connected with the heat intermedium providing mechanism between the first control mechanism and the metal hydride container and controlling the amount of the heat intermedium supplied from the heat intermedium providing mechanism to the metal hydride container.