The recent experimental data of both &pgr;&pgr;/&Kgr;&pgr; scattering and production processes, suggesting the existence of scalar &sgr; and &kgr; mesons, are reviewed. In many &pgr;&pgr;/&Kgr;&pgr; production processes the direct effects of their productions are observed, while they are, because of chiral symmetry, hidden in scattering processes, and now &sgr;(500∼600) and &kgr;(800∼900) are considered to be confirmed experimentally. Relation between &pgr;&pgr;/&Kgr;&pgr; production amplitudes and scattering amplitudes are considered. The long believed prejudice of universal &pgr;&pgr;/&Kgr;&pgr; phase through scattering and production amplitudes is explained to be not correct. Common fit of the production processes with the scattering phase shift is not valid, and the production processes should be independently analyzed from the scattering phase shift. © 2003 American Institute of Physics