1. A speech processing device comprising: an analysis unit that outputs a feature amount by performing speech detection/analysis of input speech; and a speech recognition unit that outputs a recognition result by performing speech recognition based on the feature amount, wherein said speech recognition unit comprises a phrase determination unit that determines a phrase boundary based on comparison between a hypothetical word group generated by the speech recognition and a set word representing phrase boundary, and outputs the recognition result for each phrase based on a phrase boundary determined by said phrase determination unit, and said phrase determination unit sets the phrase boundary based on a likelihood of a word representing the phrase boundary in the hypothetical word group.