An apparatus for encoding and decoding key data and key value data of a coordinate interpolator and a recording medium, on which a bitstream, into which a coordinate interpolator is encoded, is written, are provided. The bitstream includes key data encoding/decoding information, into which key data and information necessary to decode the key data are encoded, and key value data encoding/decoding information, into which key value data and information necessary to decode the key value data are encoded. The key data encoding/decoding information includes inverse DND operation information including the order of inverse DND indicating a predetermined number of cycles of inverse DND to be performed on differential data generated by entropy-decoding the bitstream in order to extend the range of the differential data.