  We investigate a stabilization of extra dimensions in a ten-dimensional
Kaluza-Klein theory and IIB supergravity. We assume (A)dS_5 x S^5
compactifcation, and calculate quantum effects to find an effective potential
for the radius of internal space. The effective potential has a minimum, and if
the universe is created on the top of the potential hill, the universe evolves
from dS_5 to AdS_5 after exponential expansion. The internal space S^5 stays to
be small and its radius becomes constant. Our model in IIB supergravity
contains the 4-form gauge field with classically vacuum expectation value,
which is role of ten-dimensional cosmological constant. If the universe evolves
into AdS, the five-dimensional Randall & Sundrum setup with stabilized dilaton
is obtained from the type IIB supergravity model.
