The present invention relates to a data transmission device and reception device in a wireless AV system. The present specification discloses a wireless data reception device comprising: a communication unit configured to receive data relating to an image from a wireless data transmission device via a wireless channel; a display unit for outputting the image; a processor configured to execute a standby mode in which a wireless data reception device or the wireless data transmission device is deactivated, and a connection reestablishment mode in which, when the wireless data reception device and the wireless data transmission device are activated, a connection setup relating to the wireless data transmission device is performed; and a memory connected to the processor and configured to store data relating to the image according to a command of the processor.