17-Cyclopropylmethyl-3,14ss-dihydroxy-4,5a-epoxy-6ss-[Nmethyl-trans-3-(3-furyl)acrylamido]morphinan hydrochloride. It has a high purity and retains constant quality after production. The 17-cyclopropylmethyl-3,14ss-dihydroxy-4,5a-epoxy-6ss-[Nmethyl-trans-3-(3-furyl)acrylamido]morphinan hydrochloride is in the form of crystals, especially A-form, B-form, and C-form crystals.