Let
be a real hypersurface
of a complex space form
,
, and suppose that the structure
vector field
is an eigen vector
field of the Ricci tensor
,
which satisfies
where
is a function.
We show that if
is
proportional to
for
any vector fields
and
orthogonal to
,
then
is a Hopf hypersurface, and if it is perpendicular to
, then
is a
ruled real hypersurface.