  From the analyses of the recent data of neutrino oscillation experiments
(especially the CHOOZ and the Super KAMIOKANDE experiments), we discuss how
these data affect the neutrinoless double beta decay ($(\beta \beta)_{0\nu}$)
rate and vice versa assuming that neutrinos are Majorana particles. For the
case that $m_1 \sim m_2 \ll m_3$ ($m_i$ are neutrino masses), we obtain, from
the data of the CHOOZ and Super KAMIOKANDE, $0.28 \le \sin^2\theta_{23} \le
0.76$ and $\sin^2\theta_{13} \le 0.05$. Combining the latter constraint with
the analysis of the "averaged" neutrino mass (< m_\nu >) appeared in $(\beta
\beta)_{0\nu}$, we find that (\frac{< m_\nu >-m_2}{m_3-m_2}<\sin^2 \theta_{13}
\le 0.05), which leads to the constraint on (< m_\nu >) as (< m_\nu > \le 0.05
m_3+(1-0.05)m_2). For the case that $m_1 \ll m_2 \sim m_3$, we find that the
data of neutrino oscillation experiments and$(\beta \beta)_{0\nu}$ imply the
constraints of mixing angles.
