PROBLEM TO BE SOLVED: To provide a compression method capable of reversibly compressing biological information with a high compression rate and a small amount of calculation and capable of flexibly responding to a specification change and various biological information and also reducing the amount of power consumption, and provide a data compression device for executing the compression method.SOLUTION: A data compression device 1 has a method provided with a step 1 for calculating a temporal difference value in the time series data of biological information, a step 2 for converting the difference value from a negative value to a positive value, and a step 3 for encoding the converted value by using a prescribed parameter in utilizing exponential Golomb coding and obtaining a codeword. In a special-purpose processor 10, a general-purpose processor 11 issues an instruction stored in an instruction memory 13 and including an exclusive instruction for executing the method, and makes a compression processing circuit 12 compress the time series data.
