A method performed by a video decoding apparatus, the method comprising: calculating an interval between a target picture including a target block to be decoded and a target reference picture that a motion vector of the target block refers to, and an interval between a picture including an adjacent block that is spatially or temporally adjacent to the target block and an adjacent reference picture that a motion vector (mvcx, mvcy) of the adjacent block refers to; calculating a scaling factor (Scale) based on the calculated intervals; scaling the motion vector (mvcx, mvcy) of the adjacent block by multiplying the motion vector (mvcx, mvcy) of the adjacent block by the scaling factor (Scale); and correcting the scaled motion vector of the adjacent block by subtracting a predetermined value "a" from an absolute value of the scaled motion vector of the adjacent block, and thereby obtaining a vector predictor candidate (mvcx', mvcy') for the motion vector of the target block, wherein when the scaling factor (Scale) has 8 bits of precision after a decimal point, the scaling and the correcting are represented by formulas: mvcx ′ = sign Scale × mvcx × abs Scale × mvcx − a + 128 > > 8 mvcy ′ = sign Scale × mvcy × abs Scale × mvcy − a + 128 > > 8 abs (): a function that returns an absolute value sign (): a function that returns a sign (1 or -1); and wherein the predetermined value "a" is greater than or equal to 1 and less than or equal to 2 N-2. calculating an interval between a target picture including a target block to be decoded and a target reference picture that a motion vector of the target block refers to, and an interval between a picture including an adjacent block that is spatially or temporally adjacent to the target block and an adjacent reference picture that a motion vector (mvcx, mvcy) of the adjacent block refers to; an interval between a target picture including a target block to be decoded and a target reference picture that a motion vector of the target block refers to, and an interval between a picture including an adjacent block that is spatially or temporally adjacent to the target block and an adjacent reference picture that a motion vector (mvcx, mvcy) of the adjacent block refers to; calculating a scaling factor (Scale) based on the calculated intervals; scaling the motion vector (mvcx, mvcy) of the adjacent block by multiplying the motion vector (mvcx, mvcy) of the adjacent block by the scaling factor (Scale); and correcting the scaled motion vector of the adjacent block by subtracting a predetermined value "a" from an absolute value of the scaled motion vector of the adjacent block, and thereby obtaining a vector predictor candidate (mvcx', mvcy') for the motion vector of the target block, wherein when the scaling factor (Scale) has 8 bits of precision after a decimal point, the scaling and the correcting are represented by formulas: mvcx ′ = sign Scale × mvcx × abs Scale × mvcx − a + 128 > > 8 mvcy ′ = sign Scale × mvcy × abs Scale × mvcy − a + 128 > > 8 abs (): a function that returns an absolute value sign (): a function that returns a sign (1 or -1); and wherein the predetermined value "a" is greater than or equal to 1 and less than or equal to 2 N-2. abs (): a function that returns an absolute value sign (): a function that returns a sign (1 or -1); and wherein the predetermined value "a" is greater than or equal to 1 and less than or equal to 2 N-2.