  Entropy of the Kerr-Newman black hole is calculated via the brick wall method
with maintaining careful attention to the contribution of superradiant scalar
modes. It turns out that the nonsuperradinat and superradiant modes
simultaneously contribute to the entropy with the same order in terms of the
brick wall cutoff $\epsilon$. In particular, the contribution of the
superradiant modes to the entropy is negative. To avoid divergency in this
method when the angular velocity tends to zero, we propose to intr oduce a
lower bound of angular velocity and to treat the case of the angular momentum
per unit mass $a=0$ separately. Moreover, from the lower bound of the angular
velocity, we obtain the $\theta$-dependence structure of the brick wall cutoff,
which natu rally requires an angular cutoff $\delta$. Finally, if the cutoff
values, $\epsilon$ and $\delta$, satisfy a proper relation between them, the
resulting entropy satisfies the area law.
