PURPOSE: To reduce a time loss in data restoration by adding a circuit that detects a data error to a register in which data are registered and then by restoring data with a signal from the detecting circuit.

CONSTITUTION: Data from input data bus 21 are applied to register 24 and coding circuit 23 that generates hamming codes. A signal coded into hamming codes is applied to check bit part 26, the output of which is applied to decoding circuit 27 to detect a data error. Data from register are applied to decoding circuit 27 to detect a data error and an error position and with the detection signals, data correcting circuit 28 corrects the data and sends corrected data to output data bus 29.