The main object of the present invention is to provide a novel agent for the treatment of spinal canal stenosis. The present invention relates to an agent for the treatment of spinal canal stenosis containing the heterocyclic derivative represented by the following general formula (1) or a pharmaceutically acceptable salt thereof as an active ingredient； In the formula (1), R 1 and R 2 are the same or different and each represents an optionally substituted aryl； R 3 and R 4 are the same or different and each represents hydrogen atom or alkyl； R 5 represents hydrogen atom, alkyl or halogen atom； Y represents N or N†’O； A represents NR 6 , and R 6 represents hydrogen atom, alkyl, etc.； D represents alkylene or alkenylene which is optionally substituted with hydroxy； E represents phenylene or a single bond； G represents O, S, etc.； and Q represents carboxy, alkoxycarbonyl, etc.
