The structural and magnetic properties of Co₂MnSi thin film grown by the ion beam sputtering method were investigated. Films grown on glass substrate at temperatures from 300°C to 600°C were polycrystalline, as were films grown on Si(100) and MgO(100) substrates at 600°C. The crystalline quality of the film improved with increasing substrate temperature. Film grown at 600°C showed the largest magnetization near the bulk value. On the other hand, film with the preferred orientation to the (001) plane was obtained by growing a Ta buffer layer before the growth of Co₂MnSi film on any substrates. The saturation magnetization increased with the increase of substrate temperature. This fact is considered to be due to the increase of the long-range order parameter.