¦Ì¢ª£å¦Ã is an undiscovered lepton flavor violating process. The discovery of the ¦Ì¢ª£å ¦Ã will be a conclusive evidence of a physics beyond the standard theory. Many well motivated theories such as super-symmetry theory predict ¦Ì¢ª£å¦Ã with sizable probability. The MEG experiment has been conducted aiming at the discovery of ¦Ì¢ª£å¦Ã, with the world's most intense DC muon beam at PSI in Switzerland. The gamma-ray and positron from decay of muon are precisely measured with advanced detectors. The result presented in the seminar is the final result of the MEG experiment with the full dataset taken from 2009 to 2013 and improved analysis algorithms. Although no significant excess of the signal is observed, the most stringent new limit 4.2x10^-13 (90% C.L.) has been set. Currently the upgraded experiment MEG-II is under preparation, and its overview will also be presented.