EMMI Workshop: SIGN 2014

We apply the histogram method to investigate the critical surface of QCD in the heavy quark region using lattice QCD simulation. In this study, we employ the reweighting technique and cumulant expansion in order to analyze the quark masses dependence of the critical surface and the quark chemical potential dependence. Finally, we show our results that a series of our methods works well to clarify the critical surface of the heavy quark region.