There is provided an image encoding device and an image encoding method, and an image processing device and an image processing method that enable easier bitstream concatenation. A structure according to the present disclosure includes: a setting unit that sets header information related to a hypothetical reference decoder in accordance with information about a position and information about reference, the information about a position and the information about reference being of the current picture of image data to be processed; and an encoding unit that encodes the image data and generates a bitstream containing the encoded data of the image data and the header information set by the setting unit. The present disclosure can be applied to image processing devices or image encoding devices, for example.