Triple point and critical point of water were estimated by constant energy molecular dynamics. The basic cell was cubic, where the central part was lattice of the cubic ice at the initial stage. The number of molecules in the basic cell was 5832. The SPCE model was assumed. The pressure and potential energy were obtained as functions of temperature. The critical point was assigned by the ratio of temperature T and the initial temperature T₀, T/T₀. The estimated triple point and critical point temperature were reasonable compared with experimental data.