  Quantum chromodynamics (QCD) claims that the major source of the nucleon
invariant mass is not the Higgs mechanism but the trace anomaly in QCD energy
momentum tensor. Although experimental and theoretical results support such
conclusion, a direct demonstration is still absent. We present the first
Lattice QCD calculation of the quark and gluon trace anomaly contributions to
the hadron masses, using the overlap fermion on the 2+1 flavor dynamical Domain
wall quark ensemble at $m_{\pi}=340$ MeV and lattice spacing $a=$0.1105 fm. The
result shows that the gluon trace anomaly contributes to most of the nucleon
mass, and the contribution in the pion state is smaller than that in others
nearly by a factor $\sim$10 since the gluon trace anomaly density inside pion
is different from the other hadrons and the magnitude is much smaller. The
gluon trace anomaly coefficient $\beta/g^3=-0.056(6)$ we obtained is consistent
with its regularization independent leading order value
$(-11+\frac{2N_f}{3})/(4\pi)^2$ perfectly.
