  Weyl semimetals with time reversal symmetry breaking are expected to show
various fascinating physical behaviors, such as intrinsic giant anomalous Hall
effect, chiral anomaly effect in the bulks, and Fermi arcs on the surfaces.
Here we report a scanning tunneling microscopy study on the magnetic Weyl
semimetal candidate Co$_3$Sn$_2$S$_2$. According to the morphology and local
density of states of the surface, we provide assignments to different surface
terminations. The measured local density of states reveals a semimetal gap of
~300 mV, which is further verified as the gap in spin-minority bands using
spin-resolved tunneling spectra. Additionally, signature for the nontrivial
surface states around 50 mV is proposed. This is further confirmed by the
observations of standing waves around a step-edge of the sample. Our
observations and their comparison with band structure calculations provide
direct yet timely evidence for the bulk and surface band structures of the
magnetic Weyl semimetal Co$_3$Sn$_2$S$_2$.
