NOVELTY - A hydrocarbon group fuel is reformed by using steam and a reformed gas obtained is cooled by using liquefied natural gas. The carbon monoxide contained in the cooled gas is converted. The carbon dioxide contained in the gas, is removed in liquid or solid state and a hydrogen gas is obtained.    USE - For fuel cell.    ADVANTAGE - The cold heat of liquefied natural gas is utilized effectively and energy required for liquefying natural gas is also recovered effectively. Since carbon-dioxide is removed, global-warming is prevented. Since carbon-dioxide and carbon-monoxide are removed from the reformed gas, storage space of the reformed gas is reduced and also construction cost of storage unit such as storage tank is reduced. The carbon-dioxide is removed economically without reducing efficiency of electricity generation in a thermal power station. High purity hydrogen is obtained economically. When hydrogen is used for fuel cell, cell voltage of the fuel cell is improved and electricity is generated efficiently.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) A hydrogen-gas making system, which has a reform-gas cooling unit for cooling reformed gas obtained from hydrocarbon group fuel, a carbon-monoxide-converting unit for converting carbon monoxide contained in the reformed gas and a carbon-dioxide removing unit for removing carbon dioxide contained in the gas, in liquid or solid state;    (2) Recovery of carbon dioxide, which involves reforming hydrocarbon group fuel by using steam, cooling the reformed gas using liquefied natural gas, converting carbon monoxide contained in the reformed gas and recovering carbon dioxide contained in the gas, in liquid or solid state; and    (3) A carbon-dioxide recovery system, which has a steam-reforming unit for reforming the hydrocarbon group fuel, a reformed-gas cooling unit for cooling the reformed gas, a carbon-monoxide-converting unit for converting carbon monoxide contained in the reformed gas, and a carbon-dioxide recovering unit for recovering the carbon dioxide contained in the gas, in liquid or solid state.    DESCRIPTION OF DRAWING(S) - The figure shows the flowchart of manufacture of hydrogen. (Drawing includes non-English language text).