1. A method of evaluating metal contamination in a semiconductor wafer that has been subjected to a heat treatment, which comprises: obtaining analysis values by analyzing a plurality of analysis points on a surface of the semiconductor wafer by a first analysis method or a second analysis method, wherein in the first analysis method, analysis values employed in evaluation decrease as an amount of contamination by a metal element that is to be evaluated increases, and in the second analysis method, analysis values employed in evaluation increase as an amount of contamination by a metal element that is to be evaluated increases; and among the plurality of analysis points, estimating a number P of analysis points to which a contaminant metal element that is to be evaluated and that has adhered to the semiconductor wafer due to contact with a contamination source is expected to diffuse due to the heat treatment; and wherein when the analysis values are obtained by the first analysis method, the analysis values of all of the analysis points are arranged in ascending order, and an analysis value Vp at a Pth point counting over from a minimal value is a value that is lower than or equal to a lower limit of a normal value specified by a probability distribution function, determination of presence of localized contamination by the metal element that is to be evaluated is made, and when the value exceeds the lower limit, determination of absence of localized contamination by the metal element that is to be evaluated is made; and when the analysis values are obtained by the second analysis method, the analysis values of all of the analysis points are arranged in ascending order, and an analysis value Vp of a Pth point counting over from a maximum value is a value that is greater than or equal to an upper limit of a normal value specified by a probability distribution function, determination of presence of localized contamination by the metal element that is to be evaluated is made, and when the value is lower than the upper limit, determination of absence of localized contamination by the metal element that is to be evaluated is made.