  In this letter, we show that the Semiclassical Einstein's Field Equation can
be recovered using the generalized entropy $S_{gen}$. This approach is
reminiscent of non-equilibrium thermodynamics. Furthermore, contrary to the
entanglement equilibrium approach of deriving the semiclassical Einstein's
equation, this approach does not require any such assumptions and still
recovers its correct form. Therefore, in a sense, we also show the validity of
the semiclassical approximation, a crucial approach for establishing a number
of important ideas such as the Hawking effect.
