In this paper, we introduce durational rules in text-to-Finger-Braille. Finger Braille is one of the communication methods for the deaf blind and it seems to be the medium most suited to real-time communication and for expressing the feelings of the speaker because of its prosody existing similarly to spoken languages. First, we analyzed duration between two Braille codes in Finger Braille and found that it can be changed according to the structure and meaning of the sentences. Second, we construct durational rules in Finger Braille based on these results. Third, the effectiveness of the rule was examined in listening experiments with a deaf blind person. As a result, it is suggested that durational prosody help listeners to have clear understanding. Finally, we made a prototype of Finger Braille receiver for teletext broadcasting system as a practical application applying this rule.