[Object] The present invention provides a novel oral low-molecular compound acting as an antagonist of the calcium receptor and having high safety. [Solution] The provided is a compound of formula (I) or a pharmaceutically acceptable salt thereof. [wherein the substitutents are defined as below: A is a single bond and the like； D is a single bond and the like； R2a and R2b are independently the same or different selected from hydrogen or halogen, and the like； R3a and R3b are independently the same or different selected from hydrogen or halogen, and the like； R4 and R5 are independently the same or different selected from hydrogen or halogen, and the like； R6 is halogen or cyano, and the like； m is an integral of 0~6； and Z is carboxy group and the like.]
