  On account of its application to the present and future analysis of the
virtual photon correction to the hadronic properties by means of lattice QCD
simulation, we initiate the study of the finite size scaling effect on the QED
correction using low energy effective theory of QCD with QED. For this purpose,
we begin with formulating a new QED on the space with finite volume. By
adapting this formalism to the partially quenched QCD with electromagnetism, we
explore the qualitative features of the finite size scaling effect on the
electromagnetic correction to the masses of pseudo-Goldstone bosons.
