The optimum operation conditions for preparing a Cu/ZnO-based multicomponent catalyst (Cu/ZnO/ZrO2/Al2O3/Ga2O3) by a coprecipitation method were established. The operation conditions for preparing the precipitate rarely affect the activity of the catalyst, whereas thoroughly washing the precipitate with distilled water to remove Na in the catalyst is greatly important for improving the activity of the catalyst. The Cu/ZnO-based multicomponent catalyst prepared under the optimum preparation conditions was highly active and stable for a long period in a continuous methanol synthesis operation at 523 K with a total pressure of 5 MPa. In the case of the methanol synthesis over the multicomponent catalyst using a recycle reactor employed as a model reactor for a practical methanol synthesis process, the conversion of CO2 in a make-up gas to methanol was more than 99.9%, indicating that the methanol synthesis over the multicomponent catalyst is extremely selective.