  An attempt to construct a cosmological scenario directly from string theory
is made. Cosmological string theory was presented by Antoniadis, Bachas, Ellis
and Nanopoulos. They also expect loop effects on cosmological string theory. In
this paper, we point out the other importance of the one-loop effect, the
finite temperature effect. The equations of motion for background geometry at
finite temperature are given. We address a problem on derivation of the
effective action at nonzero temperature.
