  We report the discovery of a microlensing planet OGLE-2012-BLG-0950Lb with
the planet/host mass ratio of $q \sim 2 \times 10^{-4}$. A long term distortion
detected in both MOA and OGLE light curve can be explained by the microlens
parallax due to the Earth's orbital motion around the Sun. Although the finite
source effect is not detected, we obtain the lens flux by the high resolution
Keck AO observation. Combining the microlens parallax and the lens flux reveal
the nature of the lens: a planet with mass of $M_{\rm p} = 35^{+17}_{-9}
M_{\oplus}$ is orbiting around a M-dwarf with mass of $M_{\rm host} =
0.56^{+0.12}_{-0.16} M_{\odot}$ with a planet-host projected separation of
$r_{\perp} =2.7^{+0.6}_{-0.7}$ AU located at $D_{\rm L} = 3.0^{+0.8}_{-1.1}$
kpc from us. This is the first mass measurement from only microlens parallax
and the lens flux without the finite source effect. In the coming space
observation-era with $Spitzer$, $K2$, $Euclid$, and $WFIRST$, we expect many
such events for which we will not be able to measure any finite source effect.
This work demonstrates an ability of mass measurements in such events.
