An image decoding device which decodes a predictive-encoded bit stream to acquire a moving image signal, the bit stream being generated by dividing a frame of the moving image signal into blocks (Ba, Bb, Bx), the image decoding device comprising: a prediction unit for dividing each block into one or more prediction regions according to a block division pattern (mc_mode0 - mc_mode7) corresponding to a motion prediction block dividing mode and performing motion prediction of a target block (Bx) by allocating a motion vector to each divided region according to the motion prediction block dividing mode; a variable length decoding unit for decoding the motion prediction block dividing mode based on a context model; wherein the variable length decoding unit is configured to use both the motion prediction block dividing mode (m(Ba)) of the Block (Ba) on the left of the target block (Bx) within the same frame and the motion prediction block dividing mode (m(Bb)) of the block (Bb) above the target block (Bx) within the same frame for the determination of the context model; and the image decoding device further comprises: a decoder for decoding the bit stream to acquire a first motion prediction mode for a first motion prediction region corresponding to the block (Bx), and to acquire a second motion prediction mode for a second motion prediction region, the second motion prediction region being obtained by dividing the first motion prediction region when the first motion prediction region is hierarchically divided; and a predictor for determining an estimated vector from an adjacent motion vector and setting the estimated vector as a motion vector for the first motion prediction region to create a prediction image when the first motion prediction mode is a skip mode, and determining an estimated vector from an adjacent motion vector and setting the estimated vector as a motion vector for the second motion prediction region to create a prediction image when the second motion prediction mode is a skip mode. a prediction unit for dividing each block into one or more prediction regions according to a block division pattern (mc_mode0 - mc_mode7) corresponding to a motion prediction block dividing mode and performing motion prediction of a target block (Bx) by allocating a motion vector to each divided region according to the motion prediction block dividing mode; a variable length decoding unit for decoding the motion prediction block dividing mode based on a context model; wherein the variable length decoding unit is configured to use both the motion prediction block dividing mode (m(Ba)) of the Block (Ba) on the left of the target block (Bx) within the same frame and the motion prediction block dividing mode (m(Bb)) of the block (Bb) above the target block (Bx) within the same frame for the determination of the context model; and the image decoding device further comprises: a decoder for decoding the bit stream to acquire a first motion prediction mode for a first motion prediction region corresponding to the block (Bx), and to acquire a second motion prediction mode for a second motion prediction region, the second motion prediction region being obtained by dividing the first motion prediction region when the first motion prediction region is hierarchically divided; and a predictor for determining an estimated vector from an adjacent motion vector and setting the estimated vector as a motion vector for the first motion prediction region to create a prediction image when the first motion prediction mode is a skip mode, and determining an estimated vector from an adjacent motion vector and setting the estimated vector as a motion vector for the second motion prediction region to create a prediction image when the second motion prediction mode is a skip mode. a decoder for decoding the bit stream to acquire a first motion prediction mode for a first motion prediction region corresponding to the block (Bx), and to acquire a second motion prediction mode for a second motion prediction region, the second motion prediction region being obtained by dividing the first motion prediction region when the first motion prediction region is hierarchically divided; and to acquire a first motion prediction mode for a first motion prediction region corresponding to the block (Bx), and to acquire a second motion prediction mode for a second motion prediction region, the second motion prediction region being obtained by dividing the first motion prediction region when the first motion prediction region is hierarchically divided; and a predictor for determining an estimated vector from an adjacent motion vector and setting the estimated vector as a motion vector for the first motion prediction region to create a prediction image when the first motion prediction mode is a skip mode, and determining an estimated vector from an adjacent motion vector and setting the estimated vector as a motion vector for the second motion prediction region to create a prediction image when the second motion prediction mode is a skip mode. determining an estimated vector from an adjacent motion vector and setting the estimated vector as a motion vector for the first motion prediction region to create a prediction image when the first motion prediction mode is a skip mode, and determining an estimated vector from an adjacent motion vector and setting the estimated vector as a motion vector for the second motion prediction region to create a prediction image when the second motion prediction mode is a skip mode.