1. A brain function data analysis method, comprising: computing, for each voxel, a connection degree vector indicating a degree of connectivity with its adjacent voxels based on diffusion tensor data capable of specifying a degree of diffusion of protons within the brain acquired on a voxel-by-voxel basis; and analyzing brain function data capable of specifying activated brain regions acquired on the voxel-by-voxel basis, based on the connection degree vector.