  We use a large, heterogeneous sample of local active galactic nuclei (AGN)
that includes Seyfert 1s, Seyfert 2s and PG quasars to investigate for the
first time the relation between black hole mass (M_BH) and mid-infrared nuclear
emission. We find a clear relation between M_BH and the 10 micron nuclear
luminosity for these local AGNs. There are no significant differences between
type 1 and type 2 objects, implying that the reprocessing of the 10 micron
nuclear emission is not severely affected by geometric and optical depth
effects. We also confirm that M_BH is related to the 2-10keV X-ray luminosity,
but only for the Compton thin galaxies. We present a theoretical basis for
these empirical relations and discuss possible reasons for the observed
scatter. Our results show that rest-frame 10 micron and hard X-ray luminosities
(especially the former, which is applicable to all AGN types) can be powerful
tools for conducting a census of black hole masses at high redshift and for
probing their cosmological evolution.
