Type III allergic inflammation model animal

The present invention provides an experimental model animal which does not develop anaphylaxis, a type I allergy, can specifically induce Arthus reaction, a type III allergy, is not affected by type I allergy and evaluates type III allergy inflammation individually, and a method of screening a reaction accelerating or inhibitory substance in a type III allergy reaction through FcγRIII by using said experimental model animal. In order to eliminate FcγRIIB that demonstrates suppressive action to response through FrγRIII, a mouse wherein the deletion mutation of both molecules of Lyn and FcγRIIB are homozygotic (Lyn − IIB − ) was generated by mating Lyn knockout mouse (Lyn −/− ) and FcγRIIB knockout mouse (FcγRIIB −/− ), and was used to measure and evaluate the deficiency of FcγRIII function in systemic passive anaphylaxis and the reduction of FcγRIII function in a bone marrow-derived mast cell, or the like.