An encoding device includes a first memory that stores image data, plural second memories that are associated with plural target pixels in the image data, each second memory storing pixel data of one or more reference pixels near the associated target pixel thereof, a controller that causes each second memory to store pixel data of the one or more reference pixels near the associated target pixel thereof specified from the image data stored in the first memory, and plural encoders that perform encoding on each of the plural target pixels by estimating pixel data of each target pixel using pixel data of the one or more reference pixels near each respective target pixel stored in the plural second memories wherein the plural target pixels have different positions in a subscanning direction such that one target pixel does not overlap with another target pixel in a main scanning direction, and the total amount of data of all of the reference pixels used by the plural encoders is equal to or less than the amount of information of one line of image data stored in the first memory.