  Charged scalar particles introduced in some extensions of the standard model
can induce $\tau$ leptonic decay at tree level. We find that with some charged
SU(2)-singlet scalar particles, like ones introduced in Zee-type models, $\tau$
leptonic decay width is always smaller than what is predicted by the standard
model, therefore they may offer a natural solution to $\tau$ decay puzzle. To
be more specific, we examine some Zee-type models in detail to see if at the
same time they are acceptable in particle physics, cosmology and astrophysics.
It is shown that $\tau$ decay data do put some constrains on these models.
