The decay phenomena of the new and old hadrons are investigated on the basis of the relativistic quark model. It is shown that the quark transition matrix elements in the mesons exactly coincide with those in the baryons. This fact facilitates us to predict the photo-decays of the L = 1 mesons, whose experiment is now in progress at Fermilab. Our analysis of the decays of the new mesons suggests the possibility of the simple SU(4) breaking pattern, that is, the SU(4) breaking factors are ascribed to the current-hadron couplings such as γV or fps in addition to the standard mass breaking, keeping the symmetric property of the strong vertices.