Abstract: [Problems] A useful compound which can be used as a pharmaceutical, in particular, an agent for treating peripheral arterial occlusive disease is provided. [Means for Solution] The present inventors have conducted extensive studies on EP4 receptor agonists, and as a result, have found that a novel pyridone compound, in which a group having an acidic group is substituted at the 1-position of the pyridone ring, the 6-position is bonded with an aromatic ring group via a linking part, and the linking part contains a nitrogen atom, has an excellent EP4 receptor agonistic action, thereby completing the present invention. Since the compound of the present invention has an excellent EP4 receptor agonistic action, it is useful as a pharmaceutical, in particular, as an agent for treating peripheral arterial occlusive disease.

Abstract: [Solving Means] The present inventors have conducted extensive studies on an EP4 receptor agonist, and as a result, found that a novel pyridone compound characterized in that the 1-position in the pyridone ring is substituted with a group having an acidic group such as a carboxyl group and the 6-position is bonded with an aromatic ring group via lower alkyl, lower alkylene, ether, or thioether, has an excellent EP4 receptor agonistic action, thereby completing the present invention. Since the compound of the present invention has an excellent EP4 receptor agonistic action and a blood flow increasing action in the hindlimb of a rat, it is useful as a pharmaceutical, in particular, an agent for treating peripheral arterial occlusive disease.