A peptide-containing composition includes a peptide and an alkaline mineral carrier, wherein an amount of the alkaline mineral carrier is 8 parts by mass or more based on 100 parts by mass of the peptide. A method for cultivating a plant includes applying a peptide-containing composition to the plant, a method for improving stability of a peptide includes mixing an alkaline mineral carrier with the peptide, and a method for storing a peptide includes storing the peptide in coexistence with an alkaline mineral carrier.
