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, wherein the phoneme string or the syllable string associated with each of the coinciding segments is a phoneme string or a syllable string associated with a segment in which a start and an end of the segment is expanded by a predetermined time; and outputting a segment in which the calculated evaluation value exceeds a predetermined threshold.