An image predictive decoding method comprising: a data extraction step for extracting, from compressed data where an image is divided into a plurality of regions and encoded, encoded data of identification information that specifies a region that is used to produce a prediction signal of a target region, encoded data of partition information identifying a region width of a first partition in the target region where prediction information associated with a neighbouring region located neighbouring the target region has been used to produce the prediction signal, and encoded data of a residual signal; a step for decoding the encoded data of the identification information to restore the identification information; a step for specifying that the target region is divided into the first partition and a second partition based on the partition information; a step for decoding the encoded data of the partition information identifying the region width of the first partition to restore the region width; a prediction signal production step for selecting a neighbouring region from among a plurality of neighbouring regions that neighbour the target region based on information decoded from encoded data of the identification information to produce a prediction signal of the first partition from a reconstructed signal by using (i) mode information that specifies an inter-picture prediction method, (ii) a reference picture number, and (iii) a motion vector, all of which are associated with the specified neighbouring region; a residual signal restoration step for restoring a reproduction residual signal of the target region from the encoded data of the residual signal; a signal production step for producing a reproduction signal of the target region based on the prediction signal of the target region and the reproduction residual signal; and a storage step for storing the reproduction signal of the target region as the reconstructed signal. a data extraction step for extracting, from compressed data where an image is divided into a plurality of regions and encoded, encoded data of identification information that specifies a region that is used to produce a prediction signal of a target region, encoded data of partition information identifying a region width of a first partition in the target region where prediction information associated with a neighbouring region located neighbouring the target region has been used to produce the prediction signal, and encoded data of a residual signal; a step for decoding the encoded data of the identification information to restore the identification information; a step for specifying that the target region is divided into the first partition and a second partition based on the partition information; a step for decoding the encoded data of the partition information identifying the region width of the first partition to restore the region width; a prediction signal production step for selecting a neighbouring region from among a plurality of neighbouring regions that neighbour the target region based on information decoded from encoded data of the identification information to produce a prediction signal of the first partition from a reconstructed signal by using (i) mode information that specifies an inter-picture prediction method, (ii) a reference picture number, and (iii) a motion vector, all of which are associated with the specified neighbouring region; a residual signal restoration step for restoring a reproduction residual signal of the target region from the encoded data of the residual signal; a signal production step for producing a reproduction signal of the target region based on the prediction signal of the target region and the reproduction residual signal; and a storage step for storing the reproduction signal of the target region as the reconstructed signal.