Abstract: It is an object of the present invention to provide, with simple and not expensive devices, a new method for generating random number with more perfectly disorder and a random number generator which is utilized in the generating method of random number. In this point of view, a noise or a signal oscillated from an oscillator is input into an A/D converter. Then, numbers of “0” and “1” are allotted at lower bit rank to output signals from the A/D converter to generate a binary random number. Then, the binary random number is divided by a given digit number to generate an n-scaled random number.