  We obtain mass and angular momentum of black holes as conserved charges in
three dimensional new massive gravity, after presenting the explicit expression
for the potential of the conserved charges. This confirms the expression of
those charges obtained in several ways, in particular through AdS/CFT
correspondence, and shows us that the first law of black hole thermodynamics is
valid in these black holes. We also comment about conserved charges in new type
black holes with the emphasis on the AdS/CFT correspondence as guiding
principle.
