  Neutrino-oscillation solutions for the atmospheric neutrino anomaly and the
solar neutrino deficit can determine the texture of the neutrino mass matrix
according to three types of neutrino mass hierarchies as Type A: $m_1^{} \ll
m_2^{} \ll m_3^{}$,
  Type B: $m_1^{} \sim m_2^{} \gg m_3^{}$, and Type C: $m_1^{} \sim m_2^{} \sim
m_3^{}$, where $m_i$ is the $i$-th generation neutrino absolute mass. The
relative sign assignments of neutrino masses in each type of mass hierarchies
play the crucial roles for the stability against quantum corrections. Actually,
two physical Majorana phases in the lepton flavor mixing matrix connect among
the relative sign assignments of neutrino masses. Therefore, in this paper we
analyze the stability of mixing angles against quantum corrections according to
three types of neutrino mass hierarchies (Type A, B, C) and two Majorana
phases. Two phases play the crucial roles for the stability of the mixing
angles against the quantum corrections.
