  We study surface charges on a generic null boundary in three dimensional
topological massive gravity (TMG). We construct the solution phase space which
involves four independent functions over the two dimensional null boundary. One
of these functions corresponds to the massive chiral propagating graviton mode
of TMG. The other three correspond to three surface charges of the theory, two
of which can always be made integrable, while the last one can become
integrable only in the absence of the chiral massive graviton flux through the
null boundary. As the null boundary symmetry algebra we obtain Heisenberg
$\oplus$ Virasoro algebra {with} a central charge proportional to the
gravitational Chern-Simons term of TMG. We also discuss that the flux of the
chiral massive gravitons appears as the (Bondi) news through the null surface.
