A magnetic characteristics measurement system includes a superconducting quantum interference device which detects a magnetization of a sample located in the vicinity of a superconducting pickup coil and outputs an electrical signal representing the magnetization. A coil is disposed to surround the superconducting pickup coil and is connected to an AC power supply so as to generate an alternating magnetic field. The AC signal output from the superconducting quantum interference device is sampled by use of an A/D converter which is operable in an audio frequency range and outputs a digital signal corresponding to the AC signal. Phase adjustment is performed so as to optimally correct a time shift of the digital signal in relation to a reference voltage signal. The phase-adjusted signal is subjected to Fourier transformation processing so as to detect harmonic components as magnetic characteristics.