To provide a swing data compression method, a swing data compression apparatus, a swing analysis apparatus, and a swing data compression program in which it is possible to reduce the quantity of swing data that is preserved while swing analysis accuracy is maintained. A swing data compression apparatus includes a storage unit that stores swing data which is output from an inertial sensor mounted on a detection target an analysis unit that analyzes a swing of the detection target using the swing data stored in the storage unit and a compression unit that compresses the swing data according to a compression rate which is set based on a result of swing analysis.
