A radio communication method in a radio communication system including a first radio communication apparatus which transmits signals according to cyclic process numbers and a second radio communication apparatus which receives the signals, the method comprising the steps of: in the second radio communication apparatus, generating, for each received signal of the received signals, a first information element, indicating a reception result of that received signal of a process number, and a second information element, indicating the reception result of that received signal of the same process number, to be added to a first information element of another received signal of another process number; transmitting response signals in response to the respective received signals, each of the response signals of a respective process number including the first information element of that respective process number and one or more second information elements of other process numbers, to the first radio communication apparatus; wherein the second radio communication apparatus changes the number of the second information elements that are included in the response signal according to a radio communication environment between the first radio communication apparatus and the second radio communication apparatus; and in the first radio communication apparatus, receiving the response signals transmitted from the second communication apparatus; and judging a reception result of a received signal of a respective process number in accordance with the first information element of that respective process number, included in the response signal corresponding to that respective process number and at least one second information element of that respective process number, included in at least one other response signal corresponding to other process number. in the second radio communication apparatus, generating, for each received signal of the received signals, a first information element, indicating a reception result of that received signal of a process number, and a second information element, indicating the reception result of that received signal of the same process number, to be added to a first information element of another received signal of another process number; transmitting response signals in response to the respective received signals, each of the response signals of a respective process number including the first information element of that respective process number and one or more second information elements of other process numbers, to the first radio communication apparatus; wherein the second radio communication apparatus changes the number of the second information elements that are included in the response signal according to a radio communication environment between the first radio communication apparatus and the second radio communication apparatus; and in the first radio communication apparatus, receiving the response signals transmitted from the second communication apparatus; and judging a reception result of a received signal of a respective process number in accordance with the first information element of that respective process number, included in the response signal corresponding to that respective process number and at least one second information element of that respective process number, included in at least one other response signal corresponding to other process number.