A transmission device comprising an image encoding unit configured to subject image data of pictures constituting moving image data to hierarchical encoding to generate a first stream having encoded image data of pictures on a low-level side representing the one or more lowest levels of a plurality of levels of a hierarchical level structure and a second stream having encoded image data of pictures on a high-level side representing the one or more highest levels of the plurality of levels of the hierarchical level structure, wherein the encoded image data has a network abstraction layer, NAL, unit structure, and wherein the image encoding unit is further configured to insert a level specified value of the first stream together with a level specified value of a bit stream formed from a combination of the first stream and the second stream into an NAL unit of a sequence parameter set, SPS. of the first stream, wherein the image encoding unit is further configured to equalize the hierarchical composition between the low-level side and the high-level side, to combine corresponding pictures on the low-level side and the high-level side into one set and to encode the same sequentially; a multiplexer configured to multiplex the first stream and the second stream generated by the image encoding unit to obtain a container in a predetermined format, insert a first descriptor describing the level specified value of the first stream into the container in correspondence with the first stream, and insert a second descriptor describing the level specified value of the bit stream formed from a combination of the first stream and the second stream into the container in correspondence with the second stream; and a transmission unit configured to transmit the container in the predetermined format obtained by the multiplexer. an image encoding unit configured to subject image data of pictures constituting moving image data to hierarchical encoding to generate a first stream having encoded image data of pictures on a low-level side representing the one or more lowest levels of a plurality of levels of a hierarchical level structure and a second stream having encoded image data of pictures on a high-level side representing the one or more highest levels of the plurality of levels of the hierarchical level structure, wherein the encoded image data has a network abstraction layer, NAL, unit structure, and wherein the image encoding unit is further configured to insert a level specified value of the first stream together with a level specified value of a bit stream formed from a combination of the first stream and the second stream into an NAL unit of a sequence parameter set, SPS. of the first stream, wherein the image encoding unit is further configured to equalize the hierarchical composition between the low-level side and the high-level side, to combine corresponding pictures on the low-level side and the high-level side into one set and to encode the same sequentially; a multiplexer configured to multiplex the first stream and the second stream generated by the image encoding unit to obtain a container in a predetermined format, insert a first descriptor describing the level specified value of the first stream into the container in correspondence with the first stream, and insert a second descriptor describing the level specified value of the bit stream formed from a combination of the first stream and the second stream into the container in correspondence with the second stream; and a transmission unit configured to transmit the container in the predetermined format obtained by the multiplexer.