A radio receiving apparatus for receiving the variable-length RLC PDU data in an RLC layer includes the buffer memory sectioned into a plurality of areas having a predetermined maximum data length of the RLC PDU data. By referring to a sequence number SN included in each received RLC PDU data, the radio receiving apparatus stores the RLC PDU data having an identical sequence number SN into an identical area, and assembles an RLC SDU data on a basis of the RLC PDU data stored in each area.