  We present the dust mass function (DMF) of 15,750 galaxies with redshift $z<
0.1$, drawn from the overlapping area of the GAMA and {\it H-}ATLAS surveys.
The DMF is derived using the density corrected $V_{\rm max}$ method, where we
estimate $V_{\rm max}$ using: (i) the normal photometric selection limit
($pV_{\rm max}$) and (ii) a bivariate brightness distribution (BBD) technique,
which accounts for two selection effects. We fit the data with a Schechter
function, and find $M^{*}=(4.65\pm0.18)\times 10^{7}\,h^2_{70}\, M_{\odot}$,
$\alpha=(1.22\pm 0.01)$, $\phi^{*}=(6.26\pm 0.28)\times 10^{-3}\,h^3_{70}\,\rm
Mpc^{-3}\,dex^{-1}$. The resulting dust mass density parameter integrated down
to $10^4\,M_{\odot}$ is $\Omega_{\rm d}=(1.11 \pm0.02)\times 10^{-6}$ which
implies the mass fraction of baryons in dust is $f_{m_b}=(2.40\pm0.04)\times
10^{-5}$; cosmic variance adds an extra 7-17\,per\,cent uncertainty to the
quoted statistical errors. Our measurements have fewer galaxies with high dust
mass than predicted by semi-analytic models. This is because the models include
too much dust in high stellar mass galaxies. Conversely, our measurements find
more galaxies with high dust mass than predicted by hydrodynamical cosmological
simulations. This is likely to be from the long timescales for grain growth
assumed in the models. We calculate DMFs split by galaxy type and find dust
mass densities of $\Omega_{\rm d}=(0.88\pm0.03)\times 10^{-6}$ and $\Omega_{\rm
d}=(0.060\pm0.005)\times 10^{-6}$ for late-types and early-types respectively.
Comparing to the equivalent galaxy stellar mass functions (GSMF) we find that
the DMF for late-types is well matched by the GMSF scaled by $(8.07\pm0.35)
\times 10^{-4}$.
