A moving-picture coding device for performing an affine transform in units of coding blocks, the moving-picture coding device comprising: a subblock-based temporal merging candidate derivation unit configured to, in a subblock-based merge mode, derive a subblock-based temporal merging candidate; an affine inheritance merging candidate derivation unit configured to, in the subblock-based merge mode, derive an affine inheritance merging candidate for inheriting an affine model of blocks neighboring a coding target block in a space domain; an affine construction merging candidate derivation unit configured to, in the subblock-based merge mode, derive an affine construction merging candidate from a plurality of motion information elements of blocks neighboring the coding target block in a space or time domain; an affine fixation merging candidate derivation unit configured to, in the subblock-based merge mode, derive an affine fixation merging candidate in which motion information of an affine control point is fixed; a subblock-based merging candidate selection unit configured to, in the subblock-based merge mode, select a subblock-based merging candidate from the subblock-based temporal merging candidate, the affine inheritance merging candidate, the affine construction merging candidate and the affine fixation merging candidate; and a coding unit configured to code information indicating whether or not the mode is the subblock-based merge mode and a merge index indicating the selected merging candidate, wherein a motion vector of each affine control point is fixed to (0, 0) in the affine fixation merging candidate, wherein the affine construction merging candidate derivation unit is further configured to compare the reference picture of each affine control point with a target reference picture and determine whether or not an affine transform is possible according to each combination of affine control points based on the condition that the reference pictures of all affine control points are the same, and wherein the target reference picture is fixed to a reference picture having reference picture index 0. a subblock-based temporal merging candidate derivation unit configured to, in a subblock-based merge mode, derive a subblock-based temporal merging candidate; an affine inheritance merging candidate derivation unit configured to, in the subblock-based merge mode, derive an affine inheritance merging candidate for inheriting an affine model of blocks neighboring a coding target block in a space domain; an affine construction merging candidate derivation unit configured to, in the subblock-based merge mode, derive an affine construction merging candidate from a plurality of motion information elements of blocks neighboring the coding target block in a space or time domain; an affine fixation merging candidate derivation unit configured to, in the subblock-based merge mode, derive an affine fixation merging candidate in which motion information of an affine control point is fixed; a subblock-based merging candidate selection unit configured to, in the subblock-based merge mode, select a subblock-based merging candidate from the subblock-based temporal merging candidate, the affine inheritance merging candidate, the affine construction merging candidate and the affine fixation merging candidate; and a coding unit configured to code information indicating whether or not the mode is the subblock-based merge mode and a merge index indicating the selected merging candidate, wherein a motion vector of each affine control point is fixed to (0, 0) in the affine fixation merging candidate, wherein the affine construction merging candidate derivation unit is further configured to compare the reference picture of each affine control point with a target reference picture and determine whether or not an affine transform is possible according to each combination of affine control points based on the condition that the reference pictures of all affine control points are the same, and wherein the target reference picture is fixed to a reference picture having reference picture index 0.