Bremsstrahlung energy spectra induced by beta ray from radionuclides ³H, ⁶³Ni, ¹⁴C, ¹⁴⁷Pm, ⁹⁰Sr, ³²P and ⁹⁰Yare calculated by using numerical data of radiation yield published by Berger et. al. and compared with those obtained from classical approximate expressions of Wu and Segré. The results for ³H, ⁶³Ni, ¹⁴C and ¹⁴⁷Pm are in good agreement with those from Segré's, while spectra from such as ³²P and ⁹⁰Y are similar to those obtained by using Wu's expression. The result for ⁹⁰Sr is in fair agreement with those from Wu's and Segré's.