Most of medical accidents around patients are depended on misidentification of human or medical articles. The accidents can be reduced, if information about the human or medical articles are managed automatically. RFID(Radio Frequency IDentification) tag can be identified automatically, since the tag uses wireless communication for identification. It is effective media to reduce the medical accidents. However, a specification of medical use RFID tag as a communication media was not discussed. In this study, the problem for realization of the tag and suitable specification of the tag are discussed. Anti metal tag is useful for medical environment. Small identification distance of the tag can be improved by suitable design of Q in the tag circuit. In the case of 125 kHz, confliction between another wireless communications can be reduced, since small number of communications are located in the band. The tag circuit can be made small in size to choice 2.45GHz band. In Japan, 0.4mm square sized tag is realized. The tag can be included in each tablets or capsules. Automatically identification is recommended in most of medical environment. Most of RFID tags are small in size and weight, and will not disturb the daily life of the patient, even if it is attached to the wristband or and so on. However, it is necessary to discuss the principal factors of RFID as wireless communication media. Medical use RFID system can not be effective and safety management system without the discussion.