The present invention provides a motion picture receiving device, comprising: image data receiving means for receiving encoded image data; decoding means for decoding the image data received by the image data receiving means; output means for outputting the image data decoded by the decoding means; and control means for determining an encoding condition of image data by communicating with a motion picture transmitting device which transmits the image data, and for controlling the decoding means to enable decoding of the image data encoded in accordance with the encoding condition; wherein, when the number of motion picture transmitting devices changes, the control means determines the encoding condition on the basis of the changed number of the motion picture transmitting devices.