Peanut allergy is IgE-mediated type-I hypersensitivity, and T helper 2 cytokines are central to those pathogenesis. We investigated the effects of the administration of chitin and chitosan on peanut-induced hypersensitivities in mouse food allergy models. Chitin and chitosan protected mice against peanut-induced anaphylaxis reactions, and the peanut-specific IgE production decreased by up to 47% with the administration of β-chitosan. The levels of IL-5, IL-13, and IL-10 were significantly suppressed in all groups (α-chitin ≥ β-chitin ≥ β-chitosan). These results suggested that the administration of chitin and chitosan from by-products of food processing are beneficial for the prevention of food allergies.