The present invention is designed to allow co-presence with other systems, and, furthermore, achieve improved spectral efficiency in cells (for example, unlicensed bands) in which pre-transmission listening is employed. The present invention provides a transmission section that transmits a DL signal, a control section that performs listening before the DL signal is transmitted, and controls DL transmission, and a receiving section that receives a delivery acknowledgement signal (ACK/NACK) in response to the DL transmission, and the control section controls a contention window size to apply to listening based on the number of NACKs in response to a predetermined period of DL transmission.