Abstract: A novel heterocyclic bisphosphonic acid derivatives represented by the following general formula (I): ##STR1## in which .circle.Het means one of the following (A) and (B): ##STR2## wherein a dotted line in (A) means that two adjacent atoms are bonded by a single bond or a double bond, ##STR3## wherein R.sup.6 and R.sup.7 may be the same or different, each represents a hydrogen atom, a lower alkyl group, a halogen atom or a hydroxyl group,R.sup.1 represents a hydrogen atom or a hydroxyl group,R.sup.2, R.sup.3, R.sup.4 and R.sup.5 may be the same or different, each represents a hydrogen atom or a lower alkyl group,"n" is 0 or 1,provided that "n" is 1 when the ring .circle.Het means (A), and "R.sup.1 " is a hydroxyl group when the ring .dotthalfcircle.Het means (B), or pharmaceutically acceptable salts thereof and bone resorption inhibitors containing the compound as an active ingredient.