A compound having calcium-receptor activation action can be used as an active ingredient of a prophylactic or therapeutic agent for diarrhea. The compound including a peptide such as ³-Glu-X-Gly (X represents an amino acid or an amino acid derivative), ³-Glu-Val-Y (Y represents an amino acid or an amino acid derivative), ³-Glu-Ala, ³-Glu-Gly, ³-Glu-Cys, ³-Glu-Met, ³-Glu-Thr, ³-Glu-Val, ³-Glu-Orn, Asp-Gly, Cys-Gly, Cys-Met, Glu-Cys, Gly-Cys, Leu-Asp, ³-Glu-Met(O), ³-Glu-³-Glu-Val, ³-Glu-Val-NH 2 , ³-Glu-Val-ol, ³-Glu-Ser, ³-Glu-Tau, ³-Glu-Cys(S-Me)(O), ³-Glu-Leu, ³-Glu-Ile, ³-Glu-t-Leu, and ³-Glu-Cys(S-Me).