In recent year, wavelet transform has been paid attention as an analysis in time-frequency domain. Furthermore, a new analytical method with the same function of wavelet transform was presented by authors. In this method, the spectrum calculation is performed by only one input data and high-speed processing performed. In this paper, by using this analytical method for the analysis of the Japanese vowel sound, and we show how a Japanese vowel sound consists of it. There are five vowel sounds in Japanese, and these vowels consist of fundamental, harmonics and high frequency waves, and so we show how these waves affect the decision of the Japanese vowel sound.