  We have fabricated a 180$^\circ$-twisted bilayer ReSe$_2$ by stacking two
centrosymmetric monolayer ReSe$_2$ flakes in opposite directions, which is
expected to lose spatial inversion symmetry. By the second harmonic generation
and angle-resolved photoemission spectroscopy, we successfully observed spatial
inversion symmetry breaking and emergent band dispersions. The band calculation
shows the finite lifting of spin degeneracy (~50 meV) distinct from natural
monolayer and bilayer ReSe$_2$. Our results demonstrate that the spin-momentum
locked state, which leads to spintronic functions and Berry-curvature-related
phenomena, can be realized even with the stacking of centrosymmetric
monolayers.
