The present disclosure provides a silicon film forming method for forming a silicon film on a workpiece having a processed surface, including: forming a seed layer by supplying a high-order aminosilane-based gas containing two or more silicon atoms in a molecular formula onto the processed surface and by having silicon adsorbed onto the processed surface; and forming a silicon film by supplying a silane-based gas not containing an amino group onto the seed layer and by depositing silicon onto the seed layer, wherein, when forming a seed layer, a process temperature is set within a range of 350 degrees C. or lower and a room temperature or higher.
