<;P>;PROBLEM TO BE SOLVED: To provide a model animal showing a hearing loss phenotype and a use thereof in order to achieve means for preventing or treating hearing loss or tinnitus. <;P>;SOLUTION: A rodent gene-modified animal shows a phenotype of aging hearing loss by lesion of one allele Ret gene. A method for screening a substance effective for preventing or treating ageing hearing loss or noise deafness includes using the rodent gene-modified animal. Meanwhile, the rodent gene-modified animal shows a phenotype of congenital deafness by lesion of both allele Ret genes. A method for screening a substance effective for treating congenital deafness includes using the rodent gene-modified animal. <;P>;COPYRIGHT: (C)2010,JPO&INPIT