It is an object to calculate a compression depth easily with high degree of accuracy. The present invention provides a compression depth calculation system 1000 configured to calculate the compression depth which is a magnitude of depression of the compressed object generated by the compression and includes a measuring apparatus 1 to be mounted on the object, and a compression depth calculating apparatus 2 configured to calculate the compression depth on the basis of information from the measuring apparatus 1. The compression depth calculation apparatus 2 calculates a coefficient of transformation on the basis of a second-order differential waveform created for the information acquired from a magnetic sensor 19 and acceleration information acquired from an acceleration sensor 13, creates a displacement waveform of a compressed portion by multiplying the acquired information by the coefficient of transformation, and calculates the compression depth on the basis of the displacement waveform.
