A radio terminal which is configured to communicate using a plurality of carrier components each having a different frequency, the radio terminal comprising: a reception start timing control means that is configured to commonly control a cycle of a reception start timing for discontinuous reception for a predetermined channel among at least one part of the component carriers assigned to the radio terminal; and a reception control means that is configured to control a reception period for discontinuous reception for said predetermined channel on said at least one part of the component carriers assigned to said radio terminal, said reception period being started from said reception start timing, wherein said reception start timing control means is configured to select one cycle of the reception start timing from among at least two cycles or more of said reception start timing each having a different length, and wherein said reception start timing control means: comprises at least one timer that, when data is received during time measurement is configured to restart and measure a predetermined period, said timer configured correspondingly to said at least one part of the component carriers assigned to said radio terminal; and is configured to transit to the cycle of the reception start timing which is longer than the current cycle of the reception start timing, if said timer reaches the predetermined period and new data is not received for the predetermined period on said at least one part of the component carriers assigned to said radio terminal and a drxShortCycle timer on all the component carriers assigned to the radio terminal expires. a reception start timing control means that is configured to commonly control a cycle of a reception start timing for discontinuous reception for a predetermined channel among at least one part of the component carriers assigned to the radio terminal; and a reception control means that is configured to control a reception period for discontinuous reception for said predetermined channel on said at least one part of the component carriers assigned to said radio terminal, said reception period being started from said reception start timing, wherein said reception start timing control means is configured to select one cycle of the reception start timing from among at least two cycles or more of said reception start timing each having a different length, and wherein said reception start timing control means: comprises at least one timer that, when data is received during time measurement is configured to restart and measure a predetermined period, said timer configured correspondingly to said at least one part of the component carriers assigned to said radio terminal; and is configured to transit to the cycle of the reception start timing which is longer than the current cycle of the reception start timing, if said timer reaches the predetermined period and new data is not received for the predetermined period on said at least one part of the component carriers assigned to said radio terminal and a drxShortCycle timer on all the component carriers assigned to the radio terminal expires. comprises at least one timer that, when data is received during time measurement is configured to restart and measure a predetermined period, said timer configured correspondingly to said at least one part of the component carriers assigned to said radio terminal; and is configured to transit to the cycle of the reception start timing which is longer than the current cycle of the reception start timing, if said timer reaches the predetermined period and new data is not received for the predetermined period on said at least one part of the component carriers assigned to said radio terminal and a drxShortCycle timer on all the component carriers assigned to the radio terminal expires.