In a series of gable-type di-copper(II) porphyrin dimers as well as the corresponding mono-copper(II)-free base porphyrin dimers, Electron Paramagnetic Resonance (EPR) spectra are measured in toluene at 77 K and 300 K, in order to clarify spin-spin coupling between the two metal spins. By comparison of the EPR data obtained in fluid solution and rigid media, we have separated contribution of exchange interaction from that of dipole-dipole coupling, which is averaged out under the fluid condition by the molecular rotational diffusion. On the basis of the line-shape analysis of the EPR spectra, the magnitudes of exchange interaction are evaluated as 0-3x10(-3) cm(-1), depending upon the spacer unit. The observed spacer dependence of exchange coupling provides a clear evidence of through-bond mechanism.