Provided are a radio transmission device and a radio transmission method which can reduce the transmission packet collision generation ratio even when no resource allocation signal is detected in retransmission. When control information outputted from a decoding unit (204) contains NACK and retransmission Grant, a retransmission resource check unit (205) determines that the resource indicated by the retransmission Grant is the retransmission resource. Moreover, when no retransmission Grant is detected and the initial transmission is a wideband transmission, the retransmission resource check unit (205) determines that no retransmission resource exists and instructs an RB allocation unit (209) to stop retransmission. Moreover, when no retransmission Grant is detected and the initial transmission is a narrow band transmission, a predetermined resource is determined to be the retransmission resource.