  We present a microscopic theory of spin torque due to diffusive spin currents
induced by spin accumulation. The obtained expression is a natural extension of
the existing one due to 'local' spin currents associated with ordinary electric
currents, and is the reciprocal of the spin motive force which induces charge
accumulation as studied recently [J. Shibata and H. Kohno, Phys. Rev. B84,
184408 (2011)]. The result is applied to a domain wall motion in a nonlocal
spin injection system, and the torque and force due to diffusive spin current
are evaluated.
