The invention provides a morphinan derivative of the Formula (I): [wherein R1 is methyl, cyclopropylmethyl or the like R2 and R3 are hydroxy, methoxy, acetoxy or the like both Y and Z are valence bonds, -C(=O)- or the like X is C2-C5 carbon chain (one of the carbon atoms may be substituted by oxygen, sulfur or nitrogen) constituting a part of the ring structure, or the like (R4)k is substituted or non-substituted benzene fused ring, carbonyl group or the like R9 is hydrogen or the like R10 and R11 are bound to represent -O-, or the like, and R6 is hydrogen or the like] or a pharmaceutically acceptable acid addition salt thereof. The invention also provides a therapeutic or prophylactic agent for urinary frequency or urinary incontinence, comprising as an effective ingredient the morphinan derivative or the pharmaceutically acceptable acid addition salt thereof a method for therapy or prophylaxis of the diseases, and use for the diseases.The compounds of the invention are useful as a new therapeutic or prophylactic agent for urinary frequency or urinary incontinence, free from side effects, and useful for the method for therapy or prophylaxis of the diseases and for use for the diseases.
