To obtain the subject new compound having excellent physical properties and excellent physiological activities and useful as a medicine.

A prostaglandin derivative selected from the derivatives of 15-deoxy-15,15-difluoroprostaglandins E, D, I, A, B and J, or a salt thereof, preferably a prostaglandin derivative of formula I [A is ethylene or the like; X is CH2 or the like; R1 is a 3-8C alkyl or the like; P, Q are each CO or the like; Z is OR3 (R3 is H or the like) or the like] or its salt (excluding 13,14- dihydro-15-deoxy-15,15-difluoro-20-methylprostaglandin E1 methyl ester), for example, 15-deoxy-15,15-difluoroprostaglandin E2 ethyl ester. For example, 15- deoxy-15,15-difluoroprostaglandin E can be synthesized by protecting the 11- hydroxy group of a compound of formula II (R2 is H or an acyl), oxidizing the 9-hydroxy group and subsequently removing the protecting group from the 11-position.