NOVELTY - The method involves washing polycrystalline silicon with the hydrochloric acid washing liquid. The polycrystalline silicon washed in hydrochloric acid washing process is washed with water. The washed polycrystalline silicon is dried until the water adhering to the surface of polycrystalline silicon is reduced or removed. The dried polycrystalline silicon is washed with hydrogen fluoride acid wash purified liquid containing hydrogen fluoride. The polycrystalline silicon washed at hydrogen fluoride acid-cleaning process is washed with water, and is dried.    USE - Purification method of polycrystalline silicon of needle shape or dendritic shape used as raw material of single crystal ingot for semiconductor or polycrystal silicon ingot and used in solar cell.    ADVANTAGE - The boron type impurity is effectively reduced or removed from the polycrystalline silicon obtained by zinc reduction process with granular quartz glass and metal impurities such as zinc, so that the purity of polycrystalline silicon is conveniently utilized.    DETAILED DESCRIPTION - The method involves immersing the washing cage containing the polycrystalline silicon in the hydrochloric acid washing liquid. The quantity of hydrochloric acid washing liquid in washing tank contains 200-300 weight part with respect to 100 weight part of polycrystalline silicon. The concentration of hydrochloric acid in hydrochloric acid washing liquid is set to 0.01-35 weight%. The polycrystalline silicon washed in hydrochloric acid washing process is taken out from a washing tank, such that washing liquid is separated from polycrystalline silicon until pH of the water in the washing tank is made neutral. The polycrystalline silicon washed with water is dried until the ratio of the surface adhered with water in polycrystalline silicon is set to 5 weight% or less. The dried polycrystalline silicon in washing cage is immersed in the washing tank for 10-48 hours in the hydrogen fluoride acid at 20-30 degrees C of liquid temperature. The quantity of the water in the washing tank is set to 200-300 weight part with respect to 100 weight part of polycrystalline silicon. The granular quartz glass contained in polycrystalline silicon is removed before hydrogen fluoride acid-cleaning process. The hydrogen fluoride acid wash purified liquid contains (in wt%) hydrogen fluoride (0-50).