The abuse of addictive drugs has been increasing world-wide and causing serious social problems. Recently, illegal drugs such as methamphetamine(MP) and 3,4-methylenedioxymethamphetamine (MDMA) have been frequently abused in Japan. The development and application of analytical methods of the abused drugs in biological specimens are very important for the prediction of and protection from the risk to human health. The biological specimens such as urine, blood and hair have been used for elucidation of the use of addictive drugs. Among them, hair is a powerful tool to supply historical information of drug abuse for a long period. In this section, analytical method for detection of addictive drugs of abuse was summarized. Our current study on MP and MDMA was also introduced.