A random number generator includes a counting value generator, an address generator, a static entropy source and a processing circuit. The counting value generator generates a first random number. The address generator generates an address signal. The static entropy source is connected with the address generator to receive the address signal and generates a second random number. The processing circuit is connected with the static entropy source and the counting value generator to receive the first random number and the second random number. After the first random number and the second random number are processed by the processing circuit, the processing circuit generates an output random number.