PROBLEM TO BE SOLVED: To provide a simple crystallization method where a crystallizer having a solidification accelerating effect of improving a crystallization speed is used in a step of crystallizing lipid containing fatty acids or glycerin fatty acid esters and fractionating it into a high melting point fraction and a low melting point fraction by compression and/or filtration, in particular, a step of fractionating a lipid composition for food or cosmetic, and to provide a fractionation method using the crystallizer.SOLUTION: Solidification of various fatty acids or glycerin fatty acid esters can be accelerated by a simple method of cooling and crystallizing molten lipid using a crystallizer where solidification accelerating particles having a specific structure are immobilized on a part or the whole of one or more surfaces of one of a crystallization tank sidewall, an agitating blade for crystallization, and a baffle plate. As a result, the crystallization speed at the time of fractionating the lipid containing the fatty acids or glycerin fatty acid esters into a high melting point fraction and a low melting point fraction is improved to increase productivity of the fractionation.
