On non-Kupka points of codimension one foliations on ${\mathbb{P}}^3$

We study the singular set of a codimension one holomorphic foliations on ${\mathbb{P}}^3$. We find a local normal form of a codimension two component of the singular set that is not of Kupka type. We also determined the number of non-Kupka points immersed in a codimension two component of the singular set of a codimension one foliation on ${\mathbb{P}}^3$.