To generate a more natural combined voice by making an order that applies an accent phrase decision rule appropriate.

This voice-combining device is provided with a text analyzing means 1 for analyzing text in a text corpus and dividing the text into morpheme strings; a compound word extracting means 2 for extracting a compound word in a morpheme string, a statistics information learning means 3 for accumulating the frequency of morpheme sets in the compound word to hold the statistics information as learning data; a compound word accent phrase deciding means 4 for calculating the degree of coupling between constituent words in the compound word, on the basis of the statistics information in the learning data 13 with respect to the compound word extracted from combination object text, applying the accent phrase decision rule, on the basis of the degree of coupling, and deciding the accent phrase of the compound word; and an acoustic processing means 5 for generating a combined voice, on the basis of accent information of the decided compound word, accent information with respect to a morpheme string which have not been authorized as a compound word and the rhythm information of each accent phrase.