In order to quickly and economically evaluate cleanliness of a metal with high representativity when quantities, compositions, etc., of non-metallic inclusion particles existing in a metal and resulting in product defects are evaluated by a sample collected during the production process of the metal, the present invention provides an evaluation method involving the steps of levitation-melting a metal piece for a predetermined time by cold crucible levitation-melting means, discharging non-metallic inclusion particles contained in the metal piece to the surface of a molten metal, and directly analyzing a curved and non-smooth sample surface after solidification by dissolving the surface and extracting and filtering the inclusions to measure or analyze the quantities of elements constituting the non-metallic inclusion particles and to determine quantity of the non-metallic inclusions.