A method of encoding a coordinate interpolator that includes key data and a key header including information regarding encoding of the key data, the key data representing the position of a key frame on a time axis. The method includes, encoding the key header and encoding the key data according to the result of the encoding performed in the encoding the key header. The encoding of the key data includes performing quantization on the key data according to the quantization bit size and generating differential data by performing differential pulse code modulation (DPCM) on the result of the quantization according to a DPCM order. The encoding of the key data also includes performing a divide-and-divide (DND) on the differential data so that a difference between a maximum and minimum of the differential data can be minimized and performing entropy encoding on the result of the DND.