  We have performed high-resolution angle-resolved photoemission spectroscopy
on single-layered cuprate Bi$_2$Sr$_2$CuO$_6$ to clarify the origin of the
pseudogap. By using various photon energies, we have succeeded in directly
observing two different pseudogaps with two different energy scales which
coexist in the antinodal region: one reflects the $d_{x^2-y^2}$-wave pairing
strength while the other has a larger energy scale suggesting an origin
distinct from superconductivity. The observed two-pseudogap behavior provides a
key to fully understand the pseudogap phenomena in cuprates.
