The present invention provides novel antigens of an allergy to shrimp, methods and kits for diagnosing an allergy to shrimp, pharmaceutical compositions comprising such an antigen, shrimps or processed products of shrimp in which such an antigen is eliminated, and a tester composition for determining the presence or absence of a shrimp antigen in an object of interest. The present invention also relates to polypeptides comprising an epitope of an antigen, kits, compositions and methods for diagnosing an allergy, comprising such a polypeptide, pharmaceutical compositions comprising such a polypeptide, and raw materials or processed products in which an antigen comprising such a polypeptide is eliminated or reduced. The present invention further relates to a tester composition for determining the presence or absence of an antigen in an object of interest.