An image encoding device is disclosed that performs an operation of generating a predicted image of a target block. The prediction operation is a type of operation that does not use neighboring pixels. The image encoding device further performs operations of performing a low-pass filter process on a prediction signal located at a boundary of the predicted image of the target block, using a decoded neighboring signal, generating a prediction residual signal of target block using the predicted image of the target block, and dividing the prediction residual signal of the target block unit block shapes designated in advance.