  We investigate how observations of the lepton flavor violating decay of the
Higgs boson ($h \to \ell\ell^\prime$) can narrow down models of neutrino mass
generation mechanisms, which were systematically studied in Refs. [1,2] by
focusing on the combination of new Yukawa coupling matrices with leptons. We
find that a wide class of models for neutrino masses can be excluded if
evidence for $h \to \ell\ell^\prime$ is really obtained in the current or
future collider experiments. In particular, simple models of Majorana neutrino
masses cannot be compatible with the observation of $h \to \ell\ell^\prime$. It
is also found that some of the simple models to generate masses of Dirac
neutrinos radiatively can be compatible with a significant rate of the $h \to
\ell\ell^\prime$ process.
