  Taking account of possible CP violation, we discuss about the constraints on
the lepton mixing angles from the neutrinoless double beta decay and from the
neutrino oscillation for the three flavour Majorana neutrinos. From the CHORUS
oscillation experiment, combined with the data of neutrinoless double beta
decay, we show that the large angle solution of (\theta_{23}) is improbable if
the neutrino mass (m_3) of the third generation is a candidate of hot dark
matters.
