  String geometry theory is one of the candidates of the non-perturbative
formulation of string theory. In this paper, from the closed bosonic sector of
string geometry theory, we derive path integrals of all order perturbative
strings on all the string backgrounds, $G_{\mu\nu}(x)$, $B_{\mu\nu}(x)$, and
$\Phi (x)$, by considering fluctuations around the string background
configurations, which are parametrized by the string backgrounds.
