A method for manufacturing polycrystalline silicon with high quality by effectively preventing undesired shape such as giving an rough surface to silicon rods or an irregularity in diameter of the silicon rods. The method for manufacturing polycrystalline silicon includes: an initial stabilizing step of deposition wherein a velocity of ejecting the raw material gas from the gas ejection ports is gradually increased; the shaping step wherein first the ejection velocity is increased at a rate higher than that in the stabilizing step and then the ejection velocity is gradually increased at a rate lower than the previous increasing rate; and a growing step wherein, after the shaping step, the ejection velocity is made slower than that at the end of the shaping step until the end of the deposition.
