Provided are novel low-molecular compounds which exhibit calcium receptor antagonist activity, and which are highly safe and orally administrable, namely, compounds having general formula (I) or pharmacologically acceptable salts thereof. In the general formula, R, R, and R are each a hydrogen atom or the like; R is methyl, ethyl, or the like; Z is carboxyl or the like; Ar is phenyl or the like; A is a single bond or the like; B is a single bond or the like; n is 0 or 1; and m is an integer of 0 to 6.