The present invention provides a novel P2X3 and/or P2X2/3 receptor antagonist.A compound represented by the formula (I):wherein Z1 is optionally protected hydroxy, etc.； Z2 is —C(═O)—, etc.； Z3a and Z3b are taken together ═O or ═S； t is an integer of 0 to 4； R4a and R4b are each independently, hydrogen or substituted or unsubstituted lower alkyl, etc.； m and n are each independently an integer of 0 to 2； k is an integer of 0 or 1； Ring A is an aromatic carbocyclic ring or a heterocyclic ring, etc.； B is aromatic carbocyclic ring-diyl or heterocyclic ring-diyl, etc.； R1a and R1b are each independently halogen, hydroxy, substituted or unsubstituted lower alkyl, etc.； R2 is substituted or unsubstituted alkyl, etc.； R3 is substituted or unsubstituted alkyl, substituted or unsubstituted aryl or a substituted or unsubstituted heterocyclic group, etc.； or its pharmaceutically acceptable salt, or a solvate thereof is provided.
