A picture decoding device configured to decode a bitstream obtained by partitioning difference information between a picture serving as a decoding target and a picture serving as a prediction target into a plurality of sub blocks and coding the partitioned sub block in a certain order, the picture decoding device comprising: a significant sub block information decoder (1006, 1008, 1001) configured to decode significant sub block information indicating whether or not all values of difference coefficients belonging to the sub block serving as the decoding target are zero; a significant difference coefficient information decoder (1006, 1008) configured to decode significant difference coefficient information indicating whether or not each value of difference coefficient at each position of difference coefficient serving as the decoding target is zero; a difference coefficient value decoder (1007, 1001) configured to decode value of difference coefficient serving as the decoding target; and a context deriver (1007, 1001) configured to derive a context for decoding the significant difference coefficient information based on sum of vertical position of the difference coefficient and horizontal position of the difference coefficient in sub block serving as the decoding target, and one of 1) sum of significant sub block information of decoded sub block neighboring the sub block serving as the decoding target at right side and lower side, 2) sum of significant difference coefficient information of difference coefficients neighboring the sub block serving as the decoding target at right side and lower side, or 3) sum of absolute value of difference coefficients neighboring the sub block serving as the decoding target at right side and lower side. a significant sub block information decoder (1006, 1008, 1001) configured to decode significant sub block information indicating whether or not all values of difference coefficients belonging to the sub block serving as the decoding target are zero; a significant difference coefficient information decoder (1006, 1008) configured to decode significant difference coefficient information indicating whether or not each value of difference coefficient at each position of difference coefficient serving as the decoding target is zero; a difference coefficient value decoder (1007, 1001) configured to decode value of difference coefficient serving as the decoding target; and a context deriver (1007, 1001) configured to derive a context for decoding the significant difference coefficient information based on sum of vertical position of the difference coefficient and horizontal position of the difference coefficient in sub block serving as the decoding target, and one of 1) sum of significant sub block information of decoded sub block neighboring the sub block serving as the decoding target at right side and lower side, 2) sum of significant difference coefficient information of difference coefficients neighboring the sub block serving as the decoding target at right side and lower side, or 3) sum of absolute value of difference coefficients neighboring the sub block serving as the decoding target at right side and lower side.