In a mesh decoding device 200, a motion vector calculation unit 202E4 sets modes of motion vectors of N (N≥1) consecutive vertices in decoding order to be the same, the N vertices constitute one group, the motion vector calculation unit 202E4 decodes, from a bit stream, a control signal capable of calculating a group size indicating a size of the group, and a flag acquisition unit 202E7: decodes a second flag for each vertex from a bit stream of a P frame in a case where a first flag indicates Yes, sets a prediction mode of the vertex to be decoded to 2 in a case where the second flag indicates Yes, and sets the prediction mode of the vertex to be decoded to a value other than 2 in a case where the second flag indicates No.