Charmonium Properties in the Deconfinement Phase from Lattice QCD

Charmonium properties have been known as suitable probes to understand the nature of QGP generated by RHIC. Lattice QCD is a powerful first-principle framework to study them, and actually has been revealed quite nontrivial features for the charmonium spectrum above the critical temperature. In this talk, I review the recent progress on the lattice QCD development on charmonium spectrum, in particular, from the viewpoint of distinction between a compact bound state and quark-antiquark scattering state in the spectrum.