PURPOSE: To obtain a superconducting magnetometer for measuring the absolute value of field by driving a plurality of superconducting quantum interference elements, having slightly different field per unit flux quantum, while connecting them in series thereby imparting information related to the absolute value of field to the output voltage characteristics for the external field.

CONSTITUTION: A modulated field is applied from a field application coil 8 to a magnetic sensor 10 connected in series with a plurality of superconducting quantum interference elements 11, 12 having slightly different field per unit flux quantum. Modulated output from the magnetic sensor 10 is amplified through an LC resonance circuit 3 and branched through a branch circuit 13 into signals 19, 20. One signal 19 is multiplied by a signal from a transmitter 7 at a multiplier 4 and the output therefrom is integrated 5 and then converted into a detection field. The other signal 20 is passed through a low-pass filter 14 where the DC component is taken out and then amplified through an amplifier 15. The flux quantum in the absolute value of field is then multiplied by an integer while a field equal to integer times of unit flux quantum is subtracted from the absolute value of the field. Finally, they are summed in order to measure the absolute value of the field.