The analysis of biological specimens is now expected to shift from multi-cell analysis to single cells to know about the molecular and cellular behavior precisely. Mass spectrometric approaches to clarify molecular profiles in a cell or very small region have been developed. Such techniques include matrix-assisted laser desorption ionization imaging mass spectrometry (MALDI-IMS), secondary-ion mass spectrometry (SIMS), single-cell MALDI and live single-cell mass spectrometry. In this paper, these methods are reviewed, and their characteristics are discussed concerning how these methods achieve our aim.