Provided is a magnetic field measurement device provided with: a magnetic sensor array in which a plurality of magnetic sensor cells capable of detecting a magnetic field in three axis directions are arranged in three dimensions, the magnetic sensor cells having a plurality of magnetic sensors each having a magnetoresistive element and a magnetic convergence plate disposed at both ends of the magnetoresistive element； a magnetic field acquisition unit for acquiring measurement data measured by the magnetic sensor array； and a signal space separation unit for performing signal separation of the spatial distribution of a magnetic field indicated by the measurement data, using as a base vector the signal vector outputted by each of the plurality of magnetic sensors when a magnetic field having an orthonormal-function spatial distribution is detected by the magnetic sensor array.
