Problems to be solved are to provide novel low-molecular compounds which exhibit calcium receptor antagonist activity, and which are highly safe and orally administrable. Means for solving the problems are the compounds having the Formula (I) or pharmaceutically acceptable salts thereof: [in the formula, each substituent is defined as follows. A: a single bond or the like D: a single bond or the like R 2a and R 2b : the same or different from each other, a hydrogen atom, a halogen atom, or the like R 3a and R 3b : the same or different from each other, a hydrogen atom, a halogen atom, or the like R 4 and R 5 : the same or different from each other, a hydrogen atom, a halogen atom, or the like R 6 : a methyl group, an ethyl group, or the like m: an integer of 0 to 6, or the like Z: a carboxy group or the like]
