  We present a Subaru/IRCS H-band image of the edge-on debris disk around the
F2V star HD 15115. We detected the debris disk, which has a bow shape and an
asymmetric surface brightness, at a projected separation of 1--3" (~50--150
AU). The disk surface brightness is ~0.5--1.5 mag brighter on the western side
than on the eastern side. We use an inclined annulus disk model to probe the
disk geometry. The model fitting suggests that the disk has an inner hole with
a radius of 86 AU and an eccentricity of 0.06. The disk model also indicates
that the amount of dust on the western side is 2.2 times larger than that on
the eastern side. A several Jupiter-mass planet may exist at $\gtrsim$45 AU and
capture grains at the Lagrangian points to open the eccentric gap. This
scenario can explain both the eccentric gap and the difference in the amount of
dust. In case of the stellar age of several 100 Myr, a dramatic planetesimal
collision possibly causes the dust to increase in the western side.
Interstellar medium interaction is also considered as a possible explanation of
the asymmetric surface brightness, however, it hardly affect large grains in
the vicinity of the inner hole.
