In this paper, 1 will try to examine the aspects of formants, based on the LPC analysis. In this analysis, five Japanese vowels (a, i, u, e, o) will experience two kinds of experiments: vowels in isolated forms, and vowels in carrier sentences. The analysis results of Japanese vowels of the Japanese natives show a peculiar feature that Japanese vowels form respective vowel groups. Each Japanese vowel makes a statistically significant difference. In the Fl analysis of the vowels grouped by the informant's sex, Japanese vowel (a) shows the greatest standard deviation without regard to the informant's sex. In the F2 analysis of Japanese vowels, each vowel has a statistically significant difference. The fact that the male's [u] shows great standard deviation means that there is a great difference of the frontness of the tongue among the Japanese males in articulating [u]. Isolated vowels and carried vowels show statistically little significance between Fl and F2 frequency values. In another contrastive analysis between the isolated vowel group and the carried vowel group, whether a vowel is articulated in isolation or in a sentence appears to have little effect on its formant frequency.