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It is generally thought that pion masses vanish when bare light quark masses$m_q$ vanish. The pions are Nambu-Goldstone bosons of chiral $SU_{A}(2)$symmetry. We discuss a possibility that even when $m_q=0$, the chiral symmetryis explicitly broken in strong coupled QCD, while it is not in weakly coupledQCD. The point is that QCD monopoles are dynamical degrees of freedom in thestrong coupled QCD. We show that the monopole quark interactions break thechiral $U_5(1)$ symmetry as well as the chiral $SU_{A}(2)$ symmetry. They areweak relative to the other chiral symmetric interactions of quarks and gluons.These weak interactions produce small pion masses as well as quark masses $\sim20$MeV in the phase with the monopole condensation. The presence of theinteractions modifies the Gell-Mann Oakes Renner relation. Using the relationwe predict the value $(-\langle\bar{q}q\rangle)^{1/3}\simeq 160$MeV. We alsoshow that the monopole quark interactions do not prevent the monopolecondensation in dual superconducting model.

Nonvanishing pion masses for vanishing bare quark masses