A random number generator circuit includes: an element generating and outputting physical random numbers; a digitizing circuit digitizing the physical random numbers to output a random number sequence tested by a testing circuit; and an error correcting code circuit including a shift register having the random number sequence input thereto, a multiplier multiplying the stored random number sequence by an error-correcting-code generating matrix, and a selector switch outputting one of an output of the shift register and an output of the multiplier in accordance with a test result obtained by the testing circuit. The error correcting code circuit outputs the output of the multiplier as a corrected random number sequence from the selector switch when the result of a test conducted by the testing circuit indicates a rejection. The testing circuit tests the corrected random number sequence when the result of the test indicates a rejection.