The sliced data structure used for a particle-based simulation using a CPU or GPU is a data structure for a calculation space. The space is a three-dimensional calculation space constructed from numerous voxels; a plurality of slices perpendicular to the Y axis is formed; numerous voxels are divided by a plurality of two-dimensional slices; the respective starting coordinates of the maximum and minimum voxels are calculated for a range of voxels in which particles are present in each of a plurality of two-dimensional slices; the voxel range is determined as a bounding box surrounded by a rectangular shape; and memory is provided for the voxels contained in the bounding boxes of each of the plurality of two-dimensional slices.