An information acquisition method includes: executing a voxel defining process to divide an area in which a signal source is assumed to be present and define a voxel division V1 specifying resolution of an image; executing a data collecting process to acquire magnetic field data resulting from measurement of a magnetic field generated in the area; and executing a reconstructing process to estimate, by using a mathematical algorithm, a direction and strength of a current of a signal source at a location of each voxel based on the acquired magnetic field data. The reconstructing process includes: calculating a Gram matrix by using a voxel division V2 defined coarser than the voxel division V1; and reconstructing, by using the Gram matrix, a direction and strength of a current of a signal source in the voxel division V1.