PURPOSE: To improve the error correction capability in the error correction coding and decoding device.

CONSTITUTION: After a fixed bit insert section 3 inserts a fixed bit to an information signal series subject to convolution correction coding, a convolution error correction coding circuit 4 encodes the result, fixed bit insert position information stored in a fixed bit insert position storage circuit 7 at a decoder side is used, and a state transition corresponding to the bit location in which the information bit is a fixed bit is limited only to one way depending on the fixed bit value (0 or 1) and the result is decoded by a convolution error correction decoding circuit 8.