Transmission device, data transmitting method, and communication system

A communication system comprising:

• a transmission device;
• and
• a plurality of reception devices that can communicate with the transmission device,
• wherein the transmission device includes
• a communication unit that communicates with a plurality of reception devices,
• a transmission data setting unit that compares the number of the reception devices as transmission targets of transmission data representing content and a predetermined threshold value and sets the transmission data to be transmitted to the reception devices to each reception device based on a result of the comparison such that a transmission rate for transmission that represents an amount of data transmission necessary to transmit the transmission data to the reception devices does not exceed a reference transmission rate representing an amount of data transmission at which data can be transmitted in the communication, and the transmission data having relatively high reproduction quality is transmitted to the reception devices as the transmission targets, and
• a transmission processing unit that concurrently transmits the transmission data set by the transmission data setting unit to the corresponding reception devices as the transmission targets.