An object of the present invention is to provide a method capable of easily producing highly pure hydrogen even in the case of using, for example, low rank coal as fuel. Another object of the present invention is to provide a hydrogen production system capable of, by utilizing the above highly pure hydrogen production method, producing the highly pure hydrogen and fixing carbon dioxide at a place where, for example, the low rank coal is produced. According to the hydrogen production method of the present invention, when gasifying, for example, the low rank coal as the fuel to produce the hydrogen, carbon monoxide in a mixture gas is converted into carbon dioxide as much as possible by a water gas shift reaction, and next, the carbon monoxide remaining after the water gas shift reaction is oxidized to the carbon dioxide by a carbon monoxide selective oxidation catalyst. As a result, the highly pure hydrogen can be easily obtained by the gas separator.