  Recent studies have shown that the primordial non-Gaussianity affects
clustering of dark matter halos through a scale-dependent bias and various
constraints on the non-Gaussianity through this scale-dependent bias have been
placed. Here we introduce the cross-correlation between the CMB lensing
potential and the galaxy angular distribution to effectively extract
information about the bias from the galaxy distribution. Then, we estimate the
error of non-linear parameter, f_NL, for the on-going CMB experiments and
galaxy surveys, such as Planck and Hyper Suprime-Cam (HSC). We found that for
the constraint on f_NL with Planck and HSC, the wide field galaxy survey is
preferable to the deep one, and the expected error on f_NL can be as small as:
\Delta f_NL ~ 20 for b_0 = 2 and \Delta f_NL ~ 10 for b_0 = 4, where b_0 is the
linear bias parameter. It is also found that future wide field galaxy survey
could achieve \Delta f_NL ~ 5 with CMB prior from Planck if one could observe
highly biased objects at higher redshift (z ~ 2).
