  We derive the subleading soft graviton theorem in a generic quantum theory of
gravity for arbitrary number of soft external gravitons and arbitrary number of
finite energy external states carrying arbitrary mass and spin. Our results are
valid to all orders in perturbation theory when the number of non-compact
space-time dimensions is six or more, but only for tree amplitudes for five or
less non-compact space-time dimensions due to enhanced contribution to loop
amplitudes from the infrared region.
