Vapor-liquid equilibrium data of the binary systems, such as MeOH-n-BuAc, EtOH-n-BuAc, n-PrOH-n-BuAc and n-BuOH-n-BuAc were measured under atmospheric pressure. The consistency of the x-y data measured was discussed by the same methods used in the previous reports.^1,2） The author determined the constants of Van Laar's equation, of Prahl's equation, and the constants of Antoine's equation for n-BuAc. At 20 ℃, the density-composition relations were also suggested for these binary systems.