  We have performed ultrahigh-resolution angle-resolved photoemission
spectroscopy to directly observe the large superconducting (SC) gap anisotropy
(GA) of YNi2B2C. The result shows large SC GA with a smooth variation along an
intersection of a Fermi surface (FS) around the $\Gamma$-Z line and nearly
isotropic SC gap values for two intersections of FSs around the X-P line but
with a point-like non-zero minimum only for one sheet. The point-like SC gap
minimum can be connected by the nesting vector reported from band calculations.
The results show unexpectedly complicated SC GA of borocarbide superconductors.
