An efficient internal combustion engine jointly using hydrogen obtained by dehydrogenation of a hydrogen supply mass. There is disclosed a hydrogen supply unit for internal combustion engine comprising hydrogen separating means, storage means for storage of separated hydrogen, means for storage of dehydrogenation products and means for addition supply of produced hydrogen to a fuel source. The hydrogen separating means for separating produced hydrogen from dehydrogenation products, includes a dehydrogenation reactor for production of hydrogen from a hydrogen supply mass using at least either the hydrogen supply mass or a hydrocarbon fuel as the fuel source, which dehydrogenation reactor on its one face is provided with a hydrogen production section bearing a dehydrogenation catalyst and on its other face is provided with an oxidation reaction section allowing passage of an exhaust from the internal combustion engine and bearing an oxidation catalyst for oxidizing any dehydrogenation products from the hydrogen supply mass to thereby bring about heat generation.