A study is done of magnetohydrodynamic (MHD) equilibrium of a self‐confined plasma ball imbedded in an atmosphere with constant pressurep0. It is found that there is more than one equilibrium state for the plasma ball and the average pressure inside the ball is less thanp0. It is also shown that the force‐free magnetic configuration cannot exist in the equilibrium state. In comparison with a spheromak, the magnetic axis in ball lightning drifts toward the center about 10%.