  Electron-positron annihilation line from a Galactic center direction was
discovered by the balloon-borne germanium gamma-ray telescope, and confirmed by
OSSE experiment of CGRO mission. Extensive observations by INTEGRAL observatory
permit to determine properties of the annihilation line from Galactic bulge.
Possible sources of $e^{+}$ already discussed are supernovae explosions,
microquasars, gamma-ray bursts, tidal disruption events, activity near black
hole of Sgr A*, $e^{+}$ generation by subrelativistic cosmic rays, or even dark
matter. One remarkable feature of the line emission is an absence of resolved
point like sources. Any model should take into account this feature. We
consider flares of low-mass stars as a possible cumulative $e^{+}$ source of
the observed annihilation line from the bulge. Our estimations show that
$e^{+}$ production by numerous flaring stars in Galaxy bulge can be
significant, or even the main source of $e^{+}$ responsible for the
annihilation line observed from the central part of our Galaxy.
