Disclosed is a methanol manufacturing system provided with: a gasification furnace (20) that gasifies biomass (21) to obtain gasified biomass (24); methanol synthesis equipment (30) that synthesizes methanol (31) using refined gas (26) derived from the obtained biomass; and a gas reforming/refining device (40) that reforms and refines natural gas (41). Methanol (31) is manufactured as follows: when hydrogen-rich gas (43) derived from the natural gas is sent from the gas reforming/refining device (40) to the methanol synthesis equipment (30) and methanol is synthesized using the biomass-derived refined gas (26) and the hydrogen-rich gas (43), a control device not shown controls the process so that an index (H2/(2CO+3CO2) = M value) indicating the proportion of carbon sources (CO, CO2) with respect to hydrogen is at least 1.05 after both gases (the biomass-derived refined gas (26) and the hydrogen-rich gas (43) derived from natural gas) are mixed.
