Provided are a compound which is superior in metabolic stability, and selectively binds to an EP4 receptor, and a medicament containing same. It has been found that a compound represented by the formula (1): wherein R 1 and R 2 are each independently a hydrogen atom or a straight chain alkyl group having a carbon number of 1 - 3, R 3 is a hydrogen atom, an alkyl group having a carbon number of 1 - 4, an alkoxyalkyl group, an aryl group, a halogen atom or a haloalkyl group, or a pharmaceutically acceptable salt thereof, has, unlike known PGI 2 analogs, a selective EP4 agonist action, and therefore, a medicament containing the compound is useful for the prophylaxis and/or treatment of immune diseases, cardiovascular diseases, cardiac diseases, respiratory diseases, ophthalmic diseases, renal diseases, hepatic diseases, bone diseases, diseases of the digestive tract, neurological diseases, skin diseases and the like.
