  We study $1/N$ corrections to a Wilson loop in holographic duality. Extending
the AdS/CFT correspondence beyond the large $N$ limit is an important but a
subtle issue, as it needs quantum gravity corrections in the gravity side. To
find a physical property of the quantum corrected geometry of near-horizon
black 0-branes previously obtained by Hyakutake, we evaluate a Euclidean string
worldsheet hanging down in the geometry, which corresponds to a rectangular
Wilson loop in the $SU(N)$ quantum mechanics with 16 supercharges at a finite
temperature with finite $N$. We find that the potential energy defined by the
Wilson loop increases due to the $1/N$ correction, therefore the quantum
gravity correction weakens the gravitational attraction.
