Abstract
Vapor-liquid equilibrium of argon is numerically simulated by Monte Carlo method. By NVT ensemble of the MC method, the pressure, volume and temperature for argon are reasonably evaluated at the outside of a vapor-liquid saturated line. Moreover, at the inside of the vapor-liquid saturated line the pressure, volume and temperature are estimated by Gibbs ensemble. However, numerical errors are seemed to be greater at a critical point and liquid phase.