  We develop a numerical scheme to make a high-frequency skymap of
gravitational-wave backgrounds (GWBs) observed via space-based interferometer.
Based on the cross-correlation technique, the intensity distribution of
anisotropic GWB can be directly reconstructed from the time-ordered data of
cross-correlation signals, with full knowledge of detector's antenna pattern
functions. We demonstrate how the planned space interferometer, LISA, can make
a skymap of GWB for a specific example of anisotropic signals. At the frequency
higher than the characteristic frequency $f_*=1/(2\pi L)$, where $L$ is the
arm-length of the detector, the reconstructed skymap free from the instrumental
noise potentially reaches the angular resolution up to the multipoles
$\ell\sim10$. The presence of instrumental noises degrades the angular
resolution. The resultant skymap has angular resolution with multipoles
$\ell\leq 6\sim7$ for the anisotropic signals with signal-to-noise ratio
S/N$>5$.
