PURPOSE: To generate a random number of a high quality by allowing an initial value to be subjected to specific folds, and also, adding a specific integer, performing a rounding processing to a result of its operation and setting it as a value in a numerical range set in advance, and outputting this rounded value as the random number.

CONSTITUTION: This circuit is provided with an initial value storage means 2 for storing an arbitrary value set in advance as an initial value, and the initial value stored therein is subjected to (natural number) folds by a first arithmetic means 3, and also, C (an integer) is added, and moreover, a rounding processing is performed to a result of its operation by a second arithmetic means 4, it is set as a value in a numerical range set in advance, and this rounded value is outputted as a random number. It is desirable that (a) in a first arithmetic means 5 is a number obtained by adding '1' to a multiple of 4, and C is a number which becomes an element each other against a multiplier of 2. Also, as for a second arithmetic means 4, it is effective to execute the rounding processing by a modulus function. In such a way, the random number of a high quality being a statistically independent number is generated.