Singing songs is one of the most popular amusements in Japan. We sing many kinds of songs at occasions such as karaoke. However, it is difficult for most of Japanese native speakers to sing English songs because of difference of phone inventory of the two languages. Nowadays, there are numerous studies of CALL (Computer Assisted Language Learning) systems including the training of English pronunciation, however, there is no system that evaluates English pronunciation of the sung English. We are now investigating how to develop such a system by analyzing English singing voice and the result of subjective evaluation. In this paper, we show the result of the subjective evaluation as well as the analysis results. As a result, we found that not only the number of mispronunciations but also other factors affect the perceived goodness of English pronunciation. We also found that pronunciation scores of the singing voice by singers with singing experience were higher than that of spoken speech, which might mean that the experience of singing improves the skill of English singing.