A radio communication apparatus is provided in Protocol Data Unit (PDU) transmission, in which the tail end (boundary) of a packet is detected based on the calculation result of an error detection calculation (Frame Check Sequence (FCS) calculation), without use of Length Indicator (LI) information. Preferably, to avoid incorrect detection, tail end presence/non-presence flag information is set in a header, and the above detection is decided to be valid when the flag information in the header part of PDU, storing the detected tail end, indicates the presence of the tail end.