Provided is an image encoding method and device capable of encoding moving image random allowing access with low delay and high compression. The image encoding method which inputs image data and encodes the image data using a reference picture about the image data and a difference between the reference picture and the image data, and performs the steps of: setting an image output availability parameter indicating that it is possible to decode the image data to output the same if past pictures fall within a fixed range have been decoded, when decoding the image data which has been encoded; calculating influenced range information indicating a range where pictures encoded in the past influence a target picture to be encoded when encoding the image data; and controlling a range of the reference picture upon encoding such that the influenced range information calculated does not exceed the image output availability parameter.