To provide an atopic dermatitis model mouse which develops the atopic dermatitis even under a clean environment and whose crisis extent is not affected by the genetic stock of the mouse, and to provide a method for screening a medicine with the model mouse.

This atopic dermatitis model mouse having characteristics (1) to (3) in a recessive heredity form, and its posterity. (1) The flare and hyperplasia of the ear skin, and itching behavior are confirmed 11 weeks after birth. (2) A serum IgA value and IgE value are high 12 weeks after birth. And (3) the hyperplasia of the ear skin and the skins around the eyes and mouth, and acute itching behaviors are observed 16 weeks after birth, and serum IgG1 value is high. An organ, tissue or cell isolated from the mouse or its posterity. A method for screening a medicine with the mouse or its posterity. And so on.