Disclosed is a pharmaceutical composition for preventing and treating addiction to morphine or preventing and inhibiting the development of tolerance to the analgesic effects of morphine, containing berberine as an effective ingredient, wherein the berberine has an inhibitory effect versus psychological dependence on abused drugs such as morphine and the increase of spontaneous locomotor activity upon administration of the drugs, The pharmaceutical composition and a Coptis japonica plant extract of the present invention, which contain berberine, are highly effective in inhibiting the aforementioned symptoms of morphine addiction, and are thus useful for prevention and treatment of addiction to abused drugs such as morphine. In addition, the pharmaceutical composition additionally containing a pharmaceutical acceptable carrier can be applied to prevent and inhibit morphine tolerance caused by repeated administration of morphine, while not affecting the analgesic effects of morphine upon a single administration.