The objective to be solved by the present invention is to provide a novel ice crystallization inhibitor which is industrially useful, which can be efficiently and stably produced in a safe process suitable for a food production without difficulty and which has excellent functions and properties. Also, the objective of the present invention is to provide an antibody which specifically reacts with the ice crystallization inhibitor, and a composition, a food, a biological sample protectant and a cosmetic which contain the ice crystallization inhibitor. Furthermore, the objective of the present invention is to provide a peptide which gives an indication of a protein having an ice crystallization inhibitory activity. The ice crystallization inhibitor according to the present invention is characterized in comprising a seed protein derived from a plant belonging to genus Vigna in Leguminosae, an allied species thereof or an improved species thereof. The ice crystallization inhibitor according to the present invention is characterized in comprising a seed protein derived from a plant belonging to genus Vigna in Leguminosae, an allied species thereof or an improved species thereof.
