First and second evaluation substrates are prepared, a direction perpendicular to a surface of the first evaluation substrate being defined by first indices, and the direction defined by the first indices being inclined from a normal direction of a surface of the second evaluation substrate. Ion implantation is performed for the first evaluation substrate in a vertical direction. Ion implantation is performed for the second evaluation substrate by using an ion beam parallel to the direction defined by the first indices. Impurity concentration distributions in a depth direction of the first and second evaluation substrates are measured. A first impurity concentration distribution on an extension line of an ion beam and a second impurity concentration distribution in a direction perpendicular to the extension line are predicted from the measured impurity concentration distributions of the first and second evaluation substrates.