To enhance transmission efficiency in the case of sending an image by reducing the information quantity.

An image signal from a camera 5 is converted into a digital signal by an A/D converter ADC 2 and compression-coded by a compression coding section 3 with a fixed parameter. Then only a main part of the compressed image data is outputted from the compression coding section 3 and the data are sent to a communication line L by a communication control section 4. The data are received by a communication control section 11 of an image receiver 10, the demodulated compressed image data main part is expanded by an expansion section 12 by referencing a parameter table 15 to which parameters used for compression coding by the compression coding section 3. Then the image data expanded by the expansion section 12 are converted into analog data by a DAC 13 and the analog data are displayed on a monitor 14.