A difference detecting unit (130) compares a captured image (811) divided into a plurality of blocks with a last captured image (812) to be compared with the captured image (811), on a block-by-block basis to detect blocks having differences from the last captured image (812), as differential blocks. In addition, a differential block selecting unit (140) selects one or more difference transmission scheduled blocks to be encoded and transmitted, from the differential blocks. In addition, a cyclic block selecting unit (160) selects one or more cyclic transmission scheduled blocks to be encoded and transmitted, from cyclic blocks other than the one or more difference transmission scheduled blocks among the plurality of blocks. A total value of amounts of code used to encode the respective one or more cyclic transmission scheduled blocks is in a range of a lower limit value and an upper limit value.