PROBLEM TO BE SOLVED: To provide a nonhuman model animal of diabetes, cardiac failure or the like, usable for the screening of a diabetes-treating agent, a cardiac failure-treating agent or the like.SOLUTION: A model animal of diabetes, cardiac failure or the like, or a part thereof comprises a knockout nonhuman animal or a part thereof from which the whole or a part of the functions of at least one gene selected from the group consisting of EBI3 gene, IL27-p28 gene and WSX-1 gene is deleted.