NOVELTY - An aggregated-form silicon (1) is accommodated in a container (2) for every predetermined mass. The aggregated-form silicon which immersed the two or more unit numbers of container in the acid in a washing tank, and accommodated portions are cleaned. The value of variation coefficient at the time of dividing the aligned container into the unit number sequentially from one side, is 0.5 or more. The ratio of variation coefficient at the time of cleaning and variation coefficient at the time of dividing the aligned container into the unit number sequentially from one side, is 0.6 or less.    USE - Washing of silicon used for raw material of single crystal silicon for semiconductors and polycrystalline silicon for solar cells.    ADVANTAGE - The method enables efficient washing of silicon without using heat exchanger, and provides silicon having high purity.    DETAILED DESCRIPTION - An aggregated-form silicon is accommodated in a container for every predetermined mass. The aggregated-form silicon which immersed the two or more unit numbers of container in the acid in a washing tank (11), and accommodated portions are cleaned. The aggregated-form silicon is divided into a several different sizes. If the aggregated-form silicon divided into each size range is accommodated in the container for every said predetermined mass, the container is divided for every unit number, and the total surface area of the aggregated form silicon in the container of the divided unit number of components is computed. When the numerical value of the total surface area of the aggregated-form silicon in the container of the unit number of components is made into a population, the value which divides the population's standard deviation by the population's average is variation coefficient, the container which accommodated the aggregated-form silicon is aligned in order of the total surface area of the aggregated-form silicon in the container. The value of variation coefficient at the time of dividing the aligned container into the unit number sequentially from one side, is 0.5 or more. The ratio of variation coefficient at the time of cleaning and variation coefficient at the time of dividing the aligned container into the unit number sequentially from one side, is 0.6 or less.    DESCRIPTION OF DRAWING(S) - The drawing shows a block diagram of washing apparatus.    Aggregated-form silicon (1)    Container (2)    Washing apparatus (10)    Washing tank (11)    Mixed acid (11a)