A difluoroprostacyclin of the following formula (V), its lower alkanol ester or its pharmaceutically acceptable salt: ##STR1## wherein A is an ethylene group, a vinylene group or an ethynylene group, R is a substituted or unsubstituted C.sub.1-10 alkyl group, a substituted or unsubstituted C.sub.1-10 alkenyl group, a substituted or unsubstituted C.sub.1-10 alkynyl group, a substituted or unsubstituted C.sub.3-8 cycloalkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryloxy group, Q is a substituted or unsubstituted C.sub.1-10 alkyl group, a substituted or unsubstituted C.sub.1-10 alkenyl group, a substituted or unsubstituted C.sub.1-10 alkynyl group, a substituted or unsubstituted C.sub.3-8 cycloalkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group.