  We discuss the synergy of the cosmic shear and CMB lensing experiments to
simultaneously constrain the neutrino mass and dark energy properties. Taking
fully account of the CMB lensing, cosmic shear, CMB anisotropies, and their
cross correlation signals, we clarify a role of each signal, and investigate
the extent to which the upcoming observations by a high-angular resolution
experiment of CMB and deep galaxy imaging survey can tightly constrain the
neutrino mass and dark energy equation-of-state parameters. Including the
primary CMB information as a prior cosmological information, the Fisher
analysis reveals that the time varying equation-of-state parameters, given by
w(a)=w_0+w_a(1-a), can be tightly constrained with the accuracies of 5% for w_0
and 15% for w_a, which are comparable to or even better than those of the
stage-III type surveys neglecting the effect of massive neutrinos. In other
words, including the neutrino mass in the parameter estimation would not
drastically alter the Figure-of-Merit estimates of dark energy parameters from
the weak lensing measurements. For the neutrino mass, a clear signal for total
neutrino mass with 0.1 eV can be detected with 2-sigma significance. The
robustness and sensitivity of these results are checked in detail by allowing
the setup of cosmic shear experiment to vary as a function of observation time
or exposure time, showing that the improvement of the constraints very weakly
depends on the survey parameters, and the results mentioned above are nearly
optimal for the dark energy parameters and the neutrino mass.
