We point out that there is a serious cosmological problem in the
supersymmetric standard model if a sterile neutrino is responsible for the
solar neutrino oscillation, and propose a possible solution to this problem. We
show that our solution induces naturally a mass of order 10^{-4} eV for the
sterile neutrino, which is deeply related to the mechanism of supersymmetry
breaking.Comment: 8 pages, no figures, minor changes, reference adde
