In conventional cases that different trees are used between luma and chroma and that luma chroma prediction including multiplication in chroma intra prediction is used, there is a problem in that a processing delay caused by the chroma intra prediction is increased in small blocks. In a case that two different trees are used between luma and chroma, in a case of an 8×8 block in a luma size, 0 is derived without decoding qt_split_cu_flag, and in a case of an 8×4/4×8 block in a luma size, 0 is derived without decoding mtt_split_cu_flag. In a case that the size of a target block is smaller than a prescribed size, a chroma intra mode is derived from any one of DC, leftward prediction, and upward prediction.