Abstract: A non-human mammal and an offspring thereof, obtainable by a somatic cell nuclear transfer method using a nucleus of a CD4-positive T cell as a nuclear donor. The non-human mammal of the present invention surely and efficiently shows allergic reactions specific to various antigens that are shown to have associations with an immune allergic disease, such as mites and cedar pollens, so that the non-human mammal can be suitably used as the developmental models of allergic diseases for studies of various diseases by studying or pursuing possibilities of applications to the diseases.