A moving picture coding device that codes moving pictures using inter-prediction based on inter-prediction information of a merge candidate in units of blocks obtained by partitioning each picture of the moving pictures, comprising: a prediction information coding unit that codes information indicating a previously designated number of merge candidates; a prediction information deriving unit (104, 205) that derives merge candidates from inter-prediction information of a prediction block neighboring to a coding target prediction block or a prediction block present at the same position as or near the coding target prediction block in a coded picture at a temporally different position from the coding target prediction block; a candidate list constructing unit (130, 230) that constructs a merge candidate list from the derived merge candidates; a candidate generating unit (134, 234) that repeatedly performs a first process for adding to the merge candidate list a merge candidate of which the motion vector has a first value, the inter-prediction mode has a second value and the reference index has a third value until the number of merge candidates included in the merge candidate list reaches the designated number of merge candidates or the third value is not smaller than a variable indicating the number of reference indices when the number of merge candidates included in the merge candidate list is smaller than the designated number of merge candidates; a candidate supplementing unit (135, 235) that, after the candidate generating unit performed the first process, repeatedly performs a second process for adding to the merge candidate list a merge candidate of which the motion vector has the first value, the inter-prediction mode has the second value and the reference index has a fourth value until the number of merge candidates included in the merge candidate list reaches the designated number of merge candidates when the number of merge candidates included in the merge candidate list is smaller than the designated number of merge candidates; and a motion-compensated prediction unit (105, 206) that selects one merge candidate from the merge candidates included in the merge candidate list of which the number of merge candidates reaches the designated number of merge candidates and performs inter-prediction on the coding target prediction block using the inter-prediction information of the selected merge candidate, wherein: the first value is (0,0); the second value is a predefined value that indicates that the inter-prediction mode is bi-prediction when a slice type of a coding target picture is a B slice; the third value is a variable that is incremented by one each time the first process occurs; and the fourth value is 0. a prediction information coding unit that codes information indicating a previously designated number of merge candidates; a prediction information deriving unit (104, 205) that derives merge candidates from inter-prediction information of a prediction block neighboring to a coding target prediction block or a prediction block present at the same position as or near the coding target prediction block in a coded picture at a temporally different position from the coding target prediction block; a candidate list constructing unit (130, 230) that constructs a merge candidate list from the derived merge candidates; a candidate generating unit (134, 234) that repeatedly performs a first process for adding to the merge candidate list a merge candidate of which the motion vector has a first value, the inter-prediction mode has a second value and the reference index has a third value until the number of merge candidates included in the merge candidate list reaches the designated number of merge candidates or the third value is not smaller than a variable indicating the number of reference indices when the number of merge candidates included in the merge candidate list is smaller than the designated number of merge candidates; a candidate supplementing unit (135, 235) that, after the candidate generating unit performed the first process, repeatedly performs a second process for adding to the merge candidate list a merge candidate of which the motion vector has the first value, the inter-prediction mode has the second value and the reference index has a fourth value until the number of merge candidates included in the merge candidate list reaches the designated number of merge candidates when the number of merge candidates included in the merge candidate list is smaller than the designated number of merge candidates; and a motion-compensated prediction unit (105, 206) that selects one merge candidate from the merge candidates included in the merge candidate list of which the number of merge candidates reaches the designated number of merge candidates and performs inter-prediction on the coding target prediction block using the inter-prediction information of the selected merge candidate, wherein: the first value is (0,0); the second value is a predefined value that indicates that the inter-prediction mode is bi-prediction when a slice type of a coding target picture is a B slice; the third value is a variable that is incremented by one each time the first process occurs; and the fourth value is 0. the first value is (0,0); the second value is a predefined value that indicates that the inter-prediction mode is bi-prediction when a slice type of a coding target picture is a B slice; the third value is a variable that is incremented by one each time the first process occurs; and the fourth value is 0.