  String geometry theory is a candidate of the non-perturbative formulation of
string theory. In order to determine the string vacuum, we need to clarify how
superstring backgrounds are described in string geometry theory. In this paper,
we show that the superstring backgrounds are embedded in configurations of the
fields of a string geometry model. Especially, we show that the configurations
satisfy the equations of motion of the string geometry model in $\alpha' \to 0$
if and only if the embedded string backgrounds satisfy their equations of
motion. This means that classical dynamics of the string backgrounds are
described as a part of classical dynamics in string geometry theory.
Furthermore, we define an energy of the configurations in the string geometry
model because they do not depend on the string geometry time. A string
background can be determined by minimizing the energy.
