Provided is a mesh data creation method allowing appropriate expression of population densities while making a balance between accuracy and granularity. In the mesh data creation method, when the number of samples in a region of reference mesh data with a predetermined size is not less than a threshold, divided mesh data is created by dividing the region of the reference mesh data. Namely, each portion with a high population density can be expressed by a fine region of mesh data and each portion with a low population density by a coarse region of mesh data. The above makes it feasible to prevent meshes from becoming too fine to ensure accuracy or, conversely, from becoming too coarse to maintain granularity, thereby resulting in failing to achieve a detailed grasp of population densities, and thus to achieve appropriate expression of population densities while making a balance between accuracy and granularity.