  We present our result of the many-flavor QCD. Information of the phase
structure of many-flavor SU(3) gauge theory is of great interest, since the
gauge theories with the walking behavior near the infrared fixed point are
candidates of new physics for the origin of the dynamical electroweak symmetry
breaking. We study the SU(3) gauge theories with 12 and 16 fundamental
fermions. Utilizing the HISQ type action which is useful to study the continuum
physics, we analyze the lattice data of the mass and the decay constant of the
pseudoscalar meson and the mass of the vector meson as well at several values
of lattice spacing and fermion mass. The finite size scaling test in the
conformal hypothesis is also performed. Our data is consistent with the
conformal scenario for Nf=12. We obtain the mass anomalous dimension $\gamma_m
\sim 0.4-0.5$. An update of $N_f=16$ study is also shown.
