  We use ultrahigh resolution, tunable, vacuum ultraviolet laser angle-resolved
photoemission spectroscopy (ARPES) to study the electronic properties of
WTe$_2$, a material that was predicted to be a type-II Weyl semimetal. The Weyl
fermion states in WTe2 were proposed to emerge at the crossing points of
electron and hole pockets; and Fermi arcs connecting electron and hole pockets
would be visible in the spectral function on (001) surface. Here we report the
observation of such Fermi arcs in WTe2 confirming the theoretical predictions.
This provides strong evidence for type-II Weyl semimetallic states in WTe2.
