  We introduce generalized almost contact structures which admit the $B$-field
transformations on odd dimensional manifolds. We provide definition of
generalized Sasakain structures from the view point of the generalized almost
contact structures. We obtain a generalized Sasakian structure on a non-compact
manifold which does not arise as a pair of ordinary Sasakian structures.
However we show that a generalized Sasakian structure on compact 3-dimensional
manifold is equivalent to a pair of Sasakian structures with the same metric.
Finally we extend a definition of a generalized almost contact structure.
