To obtain a random number generator whose linear complexity is large in comparison with a device scale and which is also cryptographically secure by sequentially changing a 1st random number series that is generated based on a 2nd random number series that is generated.

This device is provided with a 1st random number generating part 2, a 2nd random number generating part 4 and a random number converting part 6. The part 2 generates random number series (binary series) and outputs it after it is set to an initial state. Similarly, the part 4 generates random number series binary series) and outputs it after it is set to an initial state. The part 6 switches orders of inputted binary series based on binary series that are differently inputted and outputs them. Random number series (a) which are outputted from the part 2 are inputted to the part 6, and the part 6 switches the orders of the random number series (a) which are outputted from the part 2 through the procedure or operation based on random number series (b) which are outputted from the part 4 and outputs them.