Primordial black holes (PBHs) are a well motivated candidate of dark matter (DM).  There exists a wide range of PBH masses where it can comprise of the full DM density.  In this talk, I will concentrate on the ultra-light range of PBH DM (mass of PBH $\lesssim$ 10$^{17}$ g).  These ultra-light PBHs can be discovered or constrained via their Hawking radiation.  We use the observations of the 511 keV gamma-ray line and MeV gamma-ray observations at the Galactic Center to show that PBHs with masses less then 1.2 $\times$ 10$^{17}$ g cannot comprise all of the DM, setting the strongest bound on ultra-light PBHs.