PURPOSE: To prevent an error at the reduction in a reception electric field strength by applying majority decision operation ≥3 reception digital data in bit pairs and using the result of the said majority decision operation as a reception data when the reception electric field is a prescribed value or below.

CONSTITUTION: When the electric field intensity is larger than a prescribed value, an output of a comparator 8 goes to [1] and an output data of a demodulation circuit 3 is outputted to a terminal OUT via gates G6, G7. When the electric field strength is smaller than the prescribed value, data for three times' share stored in shift registers 4, 5, 6 are operated by a majority decision operating circuit 7, and the result is outputted to the terminal OUT via the gates G5, G7.