PURPOSE: To increase the steam reforming reaction pressure in the production of methanol from hydrocarbon raw material by steam reforming reaction and methanol synthesis reaction, and to save the energy consumption, by separating methane from the methanol synthesis gas by the deep-freeze separation.

CONSTITUTION: A hydrocarbon raw material such as natural gas is subjected to the steam reforming (5) with steam and/or carbon dioxide gas in the presence of a catalyst at high temperature and pressure, and the obtained gaseous mixture is made to react (30) in the presence of a catalyst without compression to convert H2, CO and CO2 in the mixture to methanol. In the above process, CH4 in the gas to be supplied to the methanol synthesis reaction 30 is removed by the deep-freeze separation 26. The steam reforming reaction pressure can be raised to 30W75kg/cm2 and the compression energy to pressurize the gas for the methanol synthesis reaction can be saved. To prevent the formation of dry ice, the CO2 in the gas is separated by contacting (16) with methanol prior to the deep- freeze separation (26), and added again to the gas after the deep-freeze separation (26).