Experimental bladder tumor was reviewed in this paper. Many investigators have been studying on the bladder carcinogenesis since occupational bladder cancers were reported. Main object in research for bladder cancer was to identify and remove environmental causes and various factors related to the development of bladder cancer. Human bladder cancers can be classified into papillary non-invasive and nodular invasive cancer. The establishment of an animal model of bladder cancer similar to human bladder cancer is important to clarify the natural history of this disease and obtain basic data on its clinical diagnosis and treatment. Bladder carcinogenesis has been known to occur in a two-stage process: initiation and promotion. Recently inhibitory effects on the bladder carcinogenesis were also studied. In this paper we described the results that have been obtained in our laboratory concerning animal bladder carcinomas.