  We report Lee-Yang zeros behavior at finite temperature and density. The
quark number densities, <n>, are calculated at the pure imaginary chemical
potential, where no sign problem occurs. Then, the canonical partition
functions, Z_C(n,T,V), up to some maximal values of n are estimated through
fitting theoretically motivated functions to <n>, which are used to compute the
Lee-Yang zeros. We study the temperature dependence of the distributions of the
Lee-Yang zeros around the pseudo-critical temperature region T/T_c = 0.84 -
1.35. In the distributions of the Lee-Yang zeros, we observe the Roberge-Weiss
phase transition at T/T_c >= 1.20. We discuss the dependence of the behaviors
of Lee-Yang zeros on the maximal value of n, so that we can estimate a reliable
infinite volume limit.
