  In transition metal compounds, due to the interactions among the charge,
spin, lattice and orbital freedoms, many intertwined orders exist with close
energies. One of the commonly observed states is the so-called nematic electron
state, which breaks the in-plane rotational symmetry. This nematic state
appears in cuprates, iron based superconductor, ultra-clean quantum Hall
systems, and Sr$_3$Ru$_2$O$_7$, etc. Nematicity may coexist, affect, cooperate
or compete with other orders. Here we show the anisotropic in-plane electronic
state and superconductivity in a recently discovered kagome metal CsV$_3$Sb$_5$
by measuring $c$-axis resistivity with the in-plane rotation of magnetic field.
We observe a twofold symmetry of superconductivity in the superconducting state
and a unique in-plane nematic electronic state above $T_c$. Interestingly these
two orders are orthogonal to each other in terms of the field direction of the
minimum resistivity. Our results shed new light in understanding non-trivial
physical properties of CsV$_3$Sb$_5$.
