a spectrum storing means which stores multiple spectrum data of white neutrons having spectrum shapes different from one another,

a testing result storing means which stores multiple SEE (Single Event Effect) counts obtained by a white neutron method conducted utilizing each of said multiple spectrum data, and

an SEE cross section calculating means which calculates SEE cross section, wherein,

said SEE cross section calculating means carries out,

a first processing including,

a processing for reading out from said spectrum storing means, predetermined spectrum data having a large flux contribution in a lower energy portion, inputting the predetermined spectrum data into the Weibull Fit function representing SEE cross section, thereby calculating a first relating value of the SEE counts, and simultaneously reading out from said spectrum storing means arbitrary spectrum data other than said predetermined spectrum data, inputting said arbitrary spectrum data into said Weibull Fit function, thereby calculating a second relating value of the SEE counts, and calculating a computed ratio as a ratio between the first and the second relating values,

a processing for reading out from said testing result storing means the SEE counts as to said predetermined spectrum data and the SEE counts as to said arbitrary spectrum data, and calculates an actually measured ratio, as a ratio therebetween, and

a processing for calculating a difference between said computed ratio and said actually measured ratio, and

the first processing then repeating the above processing multiple number of times to obtain a sum of said differences,

a second processing for changing a parameter value of said Weibull Fit function and executing said first processing repeatedly, so as to detect a parameter value to make said sum of said differences equal to or less than a predetermined value, and

a third step for generating the SEE cross section represented by the Weibull Fit function by use of said parameter value thus detected.