Study on Exotic Hadrons at B-Factories

The high luminosity e⁺e^- collision at the B-factory experiments (Belle/BaBar) have revealed rich spectra of hadron resonances in the charmonium region. Many of the newly found states do not fit to the unfilled level of the conventional spectrum. Some of them are thought to be exotic states, having sub-structure more complex than the quark anti-quark mesons. In fact, Belle has found some states with non-zero electric charge, that require a minimum quark content of . In this paper, we review the present status of studies on such exotic hadrons at the B-factory experiments.