A method of uniforming physical random numbers while concurrently maintaining a random number generating rate and ensuring security. The method sequentially inputs a plurality of physical random numbers to a shift register to hold them there, and shifts them every time a reference pulse signal rises. Physical random numbers held in the shift register are randomly selected and output by a selector based on part of them. Accordingly, physical random numbers input to the shift register are uniformed and then output even thought they have a deviation, thereby eliminating the chance of not outputting random numbers or letting others recognize the deviation of random numbers.