Disclosed is a novel prostaglandin I 2 derivative which is different from known PGI 2 analogs, or a pharmaceutically acceptable salt thereof. More specifically disclosed is a 7,7-difluoro-PGI 2 derivative (formula (1)), particularly 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, and 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.
