A method of growing silicon single crystals with a [110] crystallographic axis orientation by the Czochralski method is provided according to which a silicon seed crystal doped with a high concentration of boron is used and an included angle of a conical part during shoulder section formation is maintained within a specified range. It is thereby possible to grow large-diameter and heavy-weight dislocation-free silicon single crystals with a diameter of 300 mm or more in a stable manner, without the fear of dropping the single crystal during pulling up. Therefore, the method can be properly utilized in producing silicon single crystals as semiconductor materials.