  We make simulations with 2 flavor Wilson fermions to investigate the nature
of the end points of Roberge-Weiss (RW) first order phase transition lines. The
simulations are carried out at 9 values of the hopping parameter $\kappa$
ranging from 0.155 to 0.198 on different lattice spatial volume. The Binder
cumulants, susceptibilities and reweighted distributions of the imaginary part
of Polyakov loop are employed to determine the nature of the end points of RW
transition lines. The simulations show that the RW end points are of first
order at the values of $\kappa$ in our simulations.
