  We report the magnetic structure of room-temperature-stable, monoclinic
Mn$_3$As$_2$ at 3 K and 250 K using neutron powder diffraction measurements.
From magnetometry data, the Curie temperature of Mn$_3$As$_2$ was confirmed to
be around 270 K. Calorimetry analysis showed the presence of another transition
at 225 K. At 270 K, Mn$_3$As$_2$ undergoes a $k = 0$ ferrimagnetic ordering in
the magnetic space group $C2/m$ (#12.58) with Mn moments pointing along $b$.
Below 225 K, there is a canting of Mn moments in the $ac$ plane which produces
a multi-$k$ non-collinear magnetic structure in space group $C2/c$ (#15.85).
The components of Mn moments along $b$ follow $k=0$ ordering and the components
along $a$ and $c$ have $k = [0 0 \frac{1}{2}]$ propagation vector. The change
in the magnetic ground state with temperature provides a deeper insight into
the factors that govern magnetic ordering in Mn-As compounds.
