An address generator holds a cell list of cell data of a central cell containing a central particle and a predetermined number of surrounding cells located around the central cell in a system. The address generator designates particle data of a central particle and particles that are present around the central particle, from the cell data of the cell list, and successively updates the cell list according to predetermined rules until all the cells in the system will serve as a central cell. A memory controller reads particle data of particles that are used to calculate short-range forces that have been designated by the address generator, from a storage unit, and transfers the read particle data to a force calculator for calculating short-range forces between particles.