We examined the subject of phrase boundary determined through evaluation of disjuncture in a Japanese prosodic database. In normal fluent speech, not only word boundaries but also phrase boundaries are obscured. Such phenomena are called internal open junctures, i.e. boundaries between phrases without pause, which is one of four aspects of prosody. We investigated V-V juncture through J-ToBI labeling and listening to whole phrases to estimate degree of discontinuity and to determine the exact boundary between two phrases if possible. Different levels of discontinuities were found in various levels of junctures of phrases. Appropriate boundaries were found in most cases including some overlaps. The test materials are taken from the "Japanese MULTEXT", containing read and spontaneous speech by three male speakers and three female speakers in Tokyo dialect.