We have been developing a reliable method for prosodic word boundary detection for Japanese continuous speech based on the discrete hidden Markov modeling of fundamental frequency (F0 ) contours in mora unit. Although a favorable result was obtained for ATR continuous speech corpus as reported already, experiments were done only on closed conditions. This paper reports the results on open and speaker-independent cases using database by two speakers. On average, detection rate reached around 76.0% with insertion error rate of 18.4%. Degradation from the closed condition experiment was only a little, showing the validity of the method for open conditions.