Recently, several music information retrieval (MIR) systems have been developed which retrieve musical pieces by the user's singing voice. All of these systems use only the melody information for retrieval. Although the lyrics information is useful for retrieval, there have been few attempts to exploit lyrics in the user's input. In order to develop a MIR system that uses lyrics and melody information, lyrics recognition is needed. Lyrics recognition from a singing voice is achieved by similar technology to that of speech recognition. The difference between lyrics recognition and general speech recognition is that the input lyrics are a part of the lyrics of songs in a database. To exploit linguistic constraints maximally, we described the recognition grammar using a finite state automaton (FSA) that accepts only lyrics in the database. In addition, we carried out a "singing voice adaptation" using a speaker adaptation technique. In our experimental results, about 86% retrieval accuracy was obtained.