Novel bicycloamide derivatives (general formula (1)) and pharmaceutically acceptable salts thereof effectively inhibit DPP-IV. The bicycloamide derivatives are represented by the general formula (1): ##STR00001## Pharmaceutically acceptable salts thereof are also included (Example: (2S,4S)-1-[[(4-carbamoylbicyclo[2.2.2]oct-1-yl)amino]acetyl]-4-fluoropyrr- olidine-2-carbonitrile)).