The model for effective QCD Hamiltonian, describing bound states of “constituent” quark and antiquark, is proposed, using the Light Front (LF) formulation of QCD in the LF gauge. Zero mode of gluon field becomes independent canonical variable in this model unlike the known canonical formulations on the LF. This mode forms the “string” between quark and antiquark and bounds them. As quark and antiquark are separated by the “string”, the interaction term, related to the interaction of fermion currents in the Hamiltonian, gives zero due to locality of this interaction. We introduce the nonlocal modification of this term and investigate the resulting spectral equation for mass squared. This equation is solved analytically in the large quark mass limit. However the rotation invariance turns out to be violated with our choice of modified interaction term. We show the way to restore the invariance and discuss the possibility to obtain the spectrum describing the experimental one.