There are provided a printing apparatus which can maintain an optimal transfer rate with an external device by an optimal buffer management, and a reception buffer management method thereof. In the printing apparatus according to this invention, assume that data received in unit of packet using a wireless interface from the external device is stored in a plurality of reception buffers. A maximum receivable data amount which can be used for receiving the data from the external device is determined on the basis of the number of the confirmed empty reception buffer(s). The data transmittable amount notified of the external device is then compared with the maximum receivable data amount. When receiving a request from the external device, the printing apparatus replies to the external device to change the notified data transmittable amount, in accordance with the comparison result.