A spreadsheet software, Microsoft Excel, was used to calculate beta-ray spectra, which are necessary to obtain bremsstrahlung data for betaemitting nuclides. The results of the present calculation were compared with numerical data listed in ICRU Report 56, Appendix D. The calculated spectra for 14 nuclides among 36 nuclides of importance listed in ICRU Report were in good agreement, 20 showed slight discrepancy, and two, 204Tl and210Bi, did not agree. Among the above-mentioned 20 nuclides, those which emit single beta-ray could be made to agree with ICRU data by multiplying a newly modified correction factor. For the remaining nuclides correction was not applied because no detailed information e.g. maximum energy and intensity of beta rays is given in ICRU Report. To calculate“|Γ (γ+ iy) |2” of the Fermi function in the formula of a beta-ray energy spectrum, two types of calculation were carried out: 1) direct calculation of infinite product and 2) calculation with approximation used in ICRU Report. The results of both calculations agreed well.