It is an object of the present invention to improve the mixability of liquid hydrocarbon fuel and hydrogen gas and reduce the number of parts required for fuel supply means that supplies the two types of fuel. Disclosed is a hydrogen-fueled internal combustion engine that uses liquid hydrocarbon fuel and hydrogen gas as fuel. The hydrogen-fueled internal combustion engine comprises a fuel injection device for injecting hydrocarbon fuel; fuel supply means for supplying hydrocarbon fuel to the fuel injection device; and a microbubble generation device for generating microbubbles of hydrogen gas and mixing the generated microbubbles of hydrogen gas into liquid hydrocarbon fuel in the fuel supply means. The hydrogen gas microbubbles are supplied, for instance, to a fuel supply path (second fuel supply path) and fuel tank, which constitute the fuel supply means.