An object of the present invention is to provide an agent for treatment such as prevention or therapy of diseases associated with collagen overproduction, which has a collagen production inhibitory action. A compound represented by the formula [1] or a salt thereof has a collagen production inhibitory action and is useful for treatment such as prevention or therapy of diseases associated with collagen overproduction, such as lung fibrosis, scleroderma, nephrosclerosis and cirrhosis. wherein R1 represents an aryl group optionally substituted with one or more groups selected from a substituent group α, or the like； one of R2 and R3 represents a group represented by the formula -X1-R6 (wherein X1 represents an oxygen atom, a bond, or the like； and R6 represents an optionally substituted aryl group, or the like)； the other of R2 and R3 represents a hydrogen atom, a halogen atom, or the like； Z1 and Z2, which are the same or different, each represent a nitrogen atom or a group represented by the formula C-R7 (wherein R7 represents a hydrogen atom, a halogen atom, or the like)； and Y represents -N=N-, -S(O)O-, -C(O)-O-, -C(O)-S-, or -C(S)-O-(wherein the bond on the left side of each group binds to NH).一種如下述通式所示之化合物或其鹽：「式中，R1表示可經選自取代基群α之1個以上之基取代的芳基等；R2及R3之一表示通式-X1-R6所示之基「式中，X1表示氧原子或鍵結鍵等；R6表示可經取代之芳基等」；R2及R3之另一者表示氫原子或鹵素原子等；Z1及Z2，相同或相異，表示氮原子或通式C-R7所示之基「式中，R7表示氫原子或鹵素原子等」；Y表示-N=N-、-S(O)-O-、-C(O)-O-、-C(O)-S-或-C(S)-O-(但是，各基左側之鍵結鍵，係與NH鍵結者)」，由於具有膠原產生阻礙作用，所以在例如肺纖維化症、硬皮病、腎硬化症及肝硬變等膠原產生過剩關連之疾病之預防或治療等處置上有用。
