  We consider supersymmetric models with right-handed neutrinos where neutrino
masses are purely Dirac-type. In this model, right-handed sneutrino can be the
lightest supersymmetric particle and can be a viable candidate of cold dark
matter of the universe. Right-handed sneutrinos are never thermalized in the
early universe because of weakness of Yukawa interaction, but are effectively
produced by decays of various superparticles. We show that the present mass
density of right-handed sneutrino can be consistent with the observed dark
matter density.
