In this paper we introduce the notion of weak operator and the theory of Yetter-Drinfeld modules over a weak braided Hopf algebra with invertible antipode in a strict monoidal category. We prove that the class of such objects constitutes a non strict monoidal category. It is also shown that this category is not trivial, that is to say that it admits objects generated by the adjoint action (coaction) associated to the weak braided Hopf algebra.Keywords. Monoidal category, weak braided Hopf algebra, weak operator, Yetter-Drinfeld module.MSC 2000: 16W30, 18D10, 16T05, 16T25, 81R50. Abbreviated title: The monoidal category of YD-mod over a WBHA.