  We study QED corrections to chiral symmetry breaking in the
Nambu--Jona-Lasinio (NJL) model with two flavors of quarks. In this model, the
isospin symmetry is broken by the differences between the current quark masses
and the electromagnetic charges of the up and down quarks. To leading order in
the 1/N expansion, we calculate the effective potential of the model with
one-loop QED corrections at finite temperature.
  Evaluating the effective potential, we study the influence of the isospin
symmetry breaking on the orientation of chiral symmetry breaking.
  The current quark mass plays an essential role in maintaining the orientation
of the chiral symmetry breaking.
  If the average of the up and down quark masses is small enough, we find a
phase in which the pion field has non-vanishing expectation value and dynamical
CP violation takes place.
