A communication apparatus realizes an FEC function. In the communication apparatus, a T_FEC-pattern comparing unit calculates a code distance between a pattern of an input FEC frame falling in a certain detection window and the pre-defined T_FEC pattern for each of the detection windows one after another. Moreover, a code-distance comparing unit compares the code distances with each other to detect a code for boundary identification T_FEC between an IEEE802.3 frame and a FEC parity. Finally, a boundary-signal generating unit generates, based on the detected code for boundary identification T_FEC, a T_FEC boundary signal that indicates a detection position of the T_FEC in the input FEC frame.