A moving picture coding device using a merge mode, comprising: a merging candidate list constructor structured to construct, for a block, a merging candidate list including spatial merging candidates; a normal merging candidate selector structured to select a normal merging candidate that is used for uni-prediction L0 or uni-prediction L1 or bi-prediction from the merging candidate list; and a triangle merging candidate selector structured to select, from the merging candidate list, a first triangle merging candidate that is used for uni-prediction and a second triangle merging candidate that is used for uni-prediction, both candidates being used for predicting the block using triangle merge mode, wherein the triangle merging candidate selector derives the first triangle merging candidate designated by a first index from the merging candidate list that includes a merging candidate that is used for bi-prediction, and derives the second triangle merging candidate designated by a second index from the merging candidate list that includes a merging candidate that is used for bi-prediction excluding the first triangle merging candidate so that the first triangle merging candidate and the second triangle merging candidate are not identical characterized in that, for each candidate in the merging candidate list, the triangle merging candidate selector, using the first index and the second index, determines whether the candidate in the merging candidate list has L0 motion information and sets the L0 motion information as a triangle merging candidate in a case where the candidate in the merging candidate list has the L0 motion information, and subsequently determines whether the candidate in the merging candidate list has L1 motion information and sets the L1 motion information as another triangle merging candidate in a case where the candidate in the merging candidate list has the L1 motion information to select the first triangle merging candidate and the second triangle merging candidate. a merging candidate list constructor structured to construct, for a block, a merging candidate list including spatial merging candidates; a normal merging candidate selector structured to select a normal merging candidate that is used for uni-prediction L0 or uni-prediction L1 or bi-prediction from the merging candidate list; and a triangle merging candidate selector structured to select, from the merging candidate list, a first triangle merging candidate that is used for uni-prediction and a second triangle merging candidate that is used for uni-prediction, both candidates being used for predicting the block using triangle merge mode, wherein the triangle merging candidate selector derives the first triangle merging candidate designated by a first index from the merging candidate list that includes a merging candidate that is used for bi-prediction, and derives the second triangle merging candidate designated by a second index from the merging candidate list that includes a merging candidate that is used for bi-prediction excluding the first triangle merging candidate so that the first triangle merging candidate and the second triangle merging candidate are not identical characterized in that, for each candidate in the merging candidate list, the triangle merging candidate selector, using the first index and the second index, determines whether the candidate in the merging candidate list has L0 motion information and sets the L0 motion information as a triangle merging candidate in a case where the candidate in the merging candidate list has the L0 motion information, and subsequently determines whether the candidate in the merging candidate list has L1 motion information and sets the L1 motion information as another triangle merging candidate in a case where the candidate in the merging candidate list has the L1 motion information to select the first triangle merging candidate and the second triangle merging candidate.