Liquid waste of the tofu factory is one of the tofu residual waste that has potential pollution if it is discharged directly into the irrigation stream. In addition to potential waste pollution has the potential for fertility if used as liquid fertilizer.The aim of this research is to obtain optimum dose of liquid waste tofu as complementary fertilizer N in rice cultivation. The research was conducted by experimental method which was composed by Complete Random Design. The treatments tested were the balance of N Urea and N Waste Liquor Factory which consisted of 6 levels ie 100% N-Urea; 80% N-Urea + 20% liquid waste of the tofu factory; 60% N-Urea + 40% liquid waste of the tofu factory; 40% N-Urea + 60% liquid waste of the tofu factory; 20% N-Urea + 80% liquid waste of the tofu factory; and 100% liquid waste of the tofu factory. Liquid wastes of the tofu. factories that contain N 1,25-3,8% are able to compensate partially replacing the role of N Urea in stimulating growth and yield in rice cultivation. The results showed that the liquid waste of the tofu factory can replace some of the N element's needs in rice cultivation. The optimum dose of liquid waste tofu as a complement of N fertilizer in rice cultivation is 60% N-Urea + 40% liquid waste of the tofu factory.