A percutaneous absorption preparation which is excellent in the skin penetration of a non-narcotic analgesic buprenorphine and can sustain a high blood level in a stable state over a long period of time is provided. The percutaneous absorption preparation for administrating buprenorphine hydrochloride and/or buprenorphine, which comprises a support having on one surface thereof a plaster layer containing a pressure-sensitive adhesive, buprenorphine hydrochloride and/or buprenorphine, and a penetration enhancer, wherein the penetration enhancer comprises a combination of a monoglyceride of a fatty acid having 6 to 8 carbon atoms and isopropyl myristate, and the plaster layer contains at least 10% by weight of a monoglyceride off fatty acid having 6 to 8 carbon atoms and at least 5% by weight off isopropyl myristate, with the proviso that the content of the whole penetration enhancer ranges from 25 to 50% by weight. The combined use of the fatty acid monoglyceride and isopropyl myristate as a penetration enhancer synergistically elevates skin penetration of buprenorphine hydrochloride and/or buprenorphine.