The unanticipated price fluctuations of fuels induced by economical oil supply situations have pressed the management of the fishery industry of our country. Also, the environmental problems from global warming or exhausting CO_2 gas have pressed it. Therefore, fishery industry has strongly required to the development of alternative clean fuels that take the place of a fossil fuels. In the alternative fuels, hydrogen has attracted attention as one of an ultimate clean energy resource with recycling and reproducible characters. Because the water would be only exhausted when the hydrogen burns. The hydrogen could be produced from the processes of bio-mass, the natural energy of solar or wind power, reforming gases, sub-productions, etc., that include the hydrogen element. It was carried out in this study to attempt stable promotion in fishery industry by developing the hydrogen gas combustion engine for fishing boat and by preventing the changes in ocean environment induced by global warming. The conventional out-board gasoline engine was remade to hydrogen combustion engine that was capable of burning the hydrogen gas alternating to gasoline fuel. The remade hydrogen engine could reduce the alternating cost rather than hydrogen engine newly designed and produced would equip. It would contribute to solve the problems of environmental and/or the alternate fuel in an industrial field of the fishery. This paper presents the results of the basic performance of remade hydrogen engine, the character of exhaust gas, the cost of hydrogen gas, etc.