One object of the present invention is to provide a simple layer 2 protocol that makes it possible to adaptively retransmit data by the RLC layer according to the variation of radio channel conditions without increasing the number of PDU headers. A disclosed radio communication method includes the steps of determining whether a unit data block is to be transmitted for the first time by the RLC layer or to be retransmitted; if the unit data block is to be retransmitted, determining whether it is possible to retransmit the unit data block with a transmission time interval used for the first transmission; and if it is not possible to retransmit the unit data block with the transmission time interval used for the first transmission, setting a transmission time interval longer than the transmission time interval used for the first transmission for a downlink channel and/or an uplink channel.