  A phenomenological neutrino mass matrix is proposed to explain the solar and
atmospheric neutrino deficits and to present the neutrino as a candidate of hot
dark matter in the $3\nu_L+3\nu_R$ framework. The realization of mixing angles
which can explain the solar and atmospheric neutrino problems is taken as the
first criterion in this construction. The differences among neutrino mass
eigenvalues are introduced as a perturbation. In this scheme the structure of a
charged lepton mass matrix is not severely constrained by the solar and
atmospheric neutrino data.
