The present invention relates to a morphinan derivative represented by the following general formula (I), wherein R1 represents hydrogen, C1-6 alkyl, C6-10 aryl, etc., R2 and R3, which are the same or different, represent hydrogen, hydroxy, etc., R4 and R5 represent hydrogen, C1-6 alkyl, etc., R6 represents hydrogen, hydroxy, C1-6 alkyl, etc., X represents O or CH2, Y represents C═O, C(═O)O, etc., and m and n, which are the same or different, represent an integer of 0 to 2 (m and n are not 0 at the same time), a tautomer or stereoisomer of the compound, or a pharmaceutically acceptable salt thereof, or a solvate thereof, as well as an analgesic, antianxiety drug, etc. containing the same as an active ingredient.