A transmission circuit that transmits a multiframe including N OTN, Optical Transport Network, frame signals that each accommodate an MFAS, Multiframe Alignment Signal, and a plurality of data signals, the OTN frame signal including a plurality of subframes, the transmission circuit comprising: transmission-side signal recognition means for detecting the MFAS and recognizing an order i, wherein 1 ≤ i ≤ N, of the OTN frame signal; intra-multiframe sequence conversion means for converting a sequence of the plurality of data signals inside the multiframe in accordance with the recognized order i; transmission-side rearranging means for acquiring the sequence -converted data signals in a multiframe unit, consolidating the sequence -converted data signals into lengths equal to those of the OTN frame signals respectively, and generating N quasi-OTN frame signals being sequentially added with an MFAS; and transmission means for transmitting a multiframe including the N generated quasi-OTN frame signals; first inter-subframe sequence conversion means for replacing a sequence of a plurality of data signals of an OTN frame signal, based on a predetermined order for each of the subframes, and outputting the replaced sequence to error correction code adding means; the error correction code adding means for generating an error correction code, adding the error correction code to the OTN frame signal, and outputting an OTN frame signal added with the error correction code to intra-multiframe sequence conversion means; and first inter-subframe sequence restoring means for restoring an OTN frame signal output from the error correction code adding means by using a procedure opposite to that of the first inter-subframe sequence conversion means, and outputting the restored OTN frame signal to the intra-multiframe sequence conversion means, wherein the intra-multiframe sequence conversion means converts, inside a multiframe, a sequence of the plurality of data signals and the error correction code. transmission-side signal recognition means for detecting the MFAS and recognizing an order i, wherein 1 ≤ i ≤ N, of the OTN frame signal; intra-multiframe sequence conversion means for converting a sequence of the plurality of data signals inside the multiframe in accordance with the recognized order i; transmission-side rearranging means for acquiring the sequence -converted data signals in a multiframe unit, consolidating the sequence -converted data signals into lengths equal to those of the OTN frame signals respectively, and generating N quasi-OTN frame signals being sequentially added with an MFAS; and transmission means for transmitting a multiframe including the N generated quasi-OTN frame signals; first inter-subframe sequence conversion means for replacing a sequence of a plurality of data signals of an OTN frame signal, based on a predetermined order for each of the subframes, and outputting the replaced sequence to error correction code adding means; the error correction code adding means for generating an error correction code, adding the error correction code to the OTN frame signal, and outputting an OTN frame signal added with the error correction code to intra-multiframe sequence conversion means; and first inter-subframe sequence restoring means for restoring an OTN frame signal output from the error correction code adding means by using a procedure opposite to that of the first inter-subframe sequence conversion means, and outputting the restored OTN frame signal to the intra-multiframe sequence conversion means, wherein the intra-multiframe sequence conversion means converts, inside a multiframe, a sequence of the plurality of data signals and the error correction code.