  We study the Casimir effect for a 3-d system of ideal Bose gas in a slab
geometry with Dirichlet boundary condition. We calculate the temperature($T$)
dependence of the Casimir force below and above the Bose-Einstein condensation
temperature($T_c$). At $T\le T_c$ the Casimir force vanishes as
$[\frac{T}{T_c}]^{3/2}$. For $T\gtrsim T_c$ it weakly depends on temperature.
For $T\gg T_c$ it vanishes exponentially. At finite temperatures this force for
thermalized photons in between two plates has a classical expression which is
independent of $\hbar$. At finite temperatures the Casimir force for our system
depends on $\hbar$.
