PURPOSE: To minimize the delay required for decoding without segmenting a code by providing a means detecting all zeros of low-order bits of a syndrome register, a means controlling an output of the syndrome register and a means adding outputs of a data register and the syndrome register.

CONSTITUTION: After the input of a received word is finished to a data register 2 and a syndrome register 4, when all 0s of the low-order bits of the syndrome register 4 are detected by an all 0 detector 8, it means that a burst error of a prescribed length or below exists in the high-order bits of the syndrome register 4, and the contents of the syndrome register 4 and the data register 2 are added to apply error correction.