  It is known that each single typical pure state in an energy shell of a large
isolated quantum system well represents a thermal equilibrium state of the
system. We show that such typicality holds also for nonequilibrium steady
states (NESS's). We consider a small quantum system coupled to multiple
infinite reservoirs. In the long run, the total system reaches a unique NESS.
We identify a large Hilbert space from which pure states of the system are to
be sampled randomly and show that the typical pure states well describe the
NESS. We also point out that the irreversible relaxation to the unique NESS is
important to the typicality of the pure NESS's.
