It is intended to provide a novel bisphosphonic acid compound or a salt thereof which shows a remarkable inhibitory effect on ectopic calcification, and a pharmaceutical composition comprising the same. The present invention provides a bisphosphonic acid compound represented by the following formula(1)or a pharmaceutically acceptable salt thereof:wherein------represents a single bond or a double bond；A represents a saturated cyclic hydrocarbon or a saturated heterocyclic ring comprising a sulfur atom or an oxygen atom； and R1and R2each independently represent an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an aryloxy group, a haloalkoxy group, a haloalkly group, a halogen atom or a hydrogen atom.本發明提供一種對異位鈣化具有顯著之抑制作用之新穎雙膦酸化合物或其鹽、及含有該等之醫藥組合物。 本發明係一種雙膦酸化合物或其藥學上容許之鹽，其由下述通式(1)表示：[式中，------部分表示單鍵或雙鍵，A表示飽和環狀烴、或者包含硫原子或氧原子之飽和雜環，R1及R2分別獨立地表示烷基、烯基、炔基、烷氧基、芳氧基、鹵代烷氧基、鹵烷基、鹵素原子、氫原子]。
