We investigated the radiation fields of a self-similar slim disk and the be
havior of wind particles, which are driven by the radiation pressure of a s
elf-similar slim disk. When the accretion rate is of the order of a critica
l rate, the accretion disk must puff up in the vertical direction to form a
so-called slim disk. In contrast to a standard alpha disk, this slim disk
has two major features: i) the disk is geometrically (mildly) thick, and ii
) the radial motion is comparable to the rotational motion (advection). The
se effects make the opening angle of the disk less than 180 degrees, and th
e disk radiation fields are expected to enhance towards the center. However
, we found that trajectories of wind particles are accelerated along the di
sk surface. This indicates that the shape of the disk strongly influence th
e motion of plasma particles. Furthermore, particles lose angular momentum
by radiation drag, while gaining angular momentum from rotating radiation f
ields. Taking into consideration the Compton drag, the income and expenditu
re of angular momentum of wind particles is positive, and they tend to spre
ad out in a radial direction.