Plasma equilibrium in an artificial magnetosphere in interplanetary space is proposed to apply the idea of plasma equilibrium for magnetic sail spacecraft, which obtains a thrust force based on the interaction between solar wind particles and an artificial magnetosphere made by electromagnets onboard spacecraft. It is numerically shown that when releasing a low-velocity plasma from a magnetic sail spacecraft, an equatorial ring-current is excited around the spacecraft, which makes a larger magnetosphere and correspondingly a larger thrust level becomes possible. In our preliminary MHD and particle simulations, it is shown that thrust by magnetic sail using plasma equilibrium is more than three times larger than that of pure magnetic sail without releasing plasma, and this result shows promising feature of on magnetic sail using plasma equilibrium.