Disclosed is a technique for providing a transmission data processing method and the like capable of estimating a communicable band in a heterogeneous multi-radio network at a higher speed and minimizing the deterioration of the video quality even if an unavoidable fluctuation occurs in a band available for transmission. According to the technique, there is provided a transmission data processing method at a stage prior to data transmission by a transmission device 100 for providing the data transmission to a reception device 200 as a communication partner, including: a priority giving step of giving priority to each data of multiple pieces of data, to be transmitted to the reception device, based on a predetermined criterion; a feedback receiving step of receiving, from the reception device, feedback information on data transmitted from the transmission device to the reception device; and a distribution step of distributing, based on the priority and the feedback information received, the multiple pieces of data into a first interface and a second interface used for communication with the reception device.