  We performed angle-resolved photoemission spectroscopy with micro-focused
beam on a topological line-nodal compound CaSb2 which undergoes a
superconducting transition at the onset Tc~1.8 K, to clarify the Fermi-surface
topology relevant to the occurrence of superconductivity. We found that a
three-dimensional hole pocket at the G point is commonly seen for two types of
single-crystalline samples fabricated by different growth conditions. On the
other hand, the carrier-doping level estimated from the position of the
chemical potential was found to be sensitive to the sample fabrication
condition. The cylindrical electron pocket at the Y(C) point predicted by the
calculations is absent in one of the two samples, despite the fact that both
samples commonly show superconductivity with similar Ts's. This suggests a key
role of the three-dimensional hole pocket to the occurrence of
superconductivity, and further points to an intriguing possibility to control
the topological nature of superconductivity by carrier tuning in CaSb2.
