To provide a peptide composition which reduces the antigenicity of -lactoglobulin, adjusts the Th1 cell-Th2 cell balance of helper T cell, and controls the production of a specific IgE-dependent type I allergy.

It has been found that a peptide composition prepared by hydrolyzing -lactoglobulin with alkalase or trypsin has an action for promoting the production of IFN- and inhibiting the production of IL-4. In addition, a peptide having the activity was isolated and purified from the hydrolysate, and the peptide sequence of the peptide could be identified.