  We derive the scalar potential in zero mode effective action arising from a
de Sitter brane embedded in five dimensions with bulk cosmological constant
$\Lambda$. The scalar potential for a scalar field canonically normalized is
given by the sum of exponential potentials. In the case of $\Lambda=0$ and
$\Lambda>0$, we point out that the scalar potential has an unstable local
maximum at the origin and exponentially vanishes for large positive scalar
field. In the case of $\Lambda<0$, the scalar potential has an unstable local
maximum at the origin and a stable local minimum, it is shown that the positive
cosmological constant in brane is reduced by negative potential energy of
scalar at minimum.
