1. A method for speech retrieval, comprising: acquiring a keyword designated by a character string, and a phoneme string or a syllable string; detecting one or more coinciding segments by comparing a character string that is a recognition result of word speech recognition with words as recognition units performed for speech data to be retrieved and the character string of the keyword; calculating an evaluation value of each of the one or more coinciding segments by using the phoneme string or the syllable string of the keyword to evaluate a phoneme string or a syllable string that is recognized in each of the detected one or more coinciding segments and that is a recognition result of phoneme speech recognition with phonemes or syllables as recognition units performed for the speech data; and outputting a segment in which the calculated evaluation value exceeds a predetermined threshold.