Cycloalkylcarbonylamino acid ester derivatives, which are raw material intermediates for a novel cycloalkane carboxamide derivative having an action that selectively inhibits cathepsin K, and a production process thereof, are provided.A cycloalkylcarbonylamino acid ester derivative represented by formula (I), or a pharmaceutically acceptable salt thereof: (wherein, R1 and R2 represent alkyl groups, alkenyl groups, alkynyl groups, aromatic hydrocarbon groups, heterocyclic groups, etc., R8 represents an alkyl group having 1 to 6 carbon atoms, and ring A represents a cyclic alkylidene group having 5, 6 or 7 carbon atoms).