To enable to adapt to a stuff mode of a frame or a packet transmitted from an opposite apparatus and to normally receive data even when the stuff mode of the opposite apparatus is unknown.

A transmission apparatus comprises: a bit stuff processing unit that performs a bit stuffing process to a data of a input frame; a byte stuff processing unit that performs a byte stuffing process to a replicated data; an FCS check unit that performs an FCS process to outputs from the bit stuff processing unit and the byte stuff processing unit respectively; and a stuff mode determining unit that determines a stuff mode of an opposite transmission apparatus depending on a code conversion result in the bit stuff processing unit and the byte stuff processing unit respectively and a stuff mode of an apparatus that detects a data with a normal FCS by the FCS check unit.