Accurate voice humming transcription and efficient indexing schemes are essential for a large-scale humming-based music retrieval system. Although many researches have been done to develop such schemes, their performances are not still satisfactory. In our previous works, we proposed (i) a new voice query transcription scheme , (ii) a popularity-adaptive indexing structure called FAI  for fast retrieval, and (iii) a semisupervised relevance feedback and query reformulation scheme based on a genetic algorithm  in order to improve retrieval efficiency. In this demonstration, we extend our efforts to a mobile environment and develop a prototype mobile music retrieval system called M-MUSICS. Our focus in this implementation includes versatile user interface for easy querying and browsing on a typical mobile device such as PDA phone and satisfactory performance in a wireless mobile environment. We report some of the results.