Jets issuing through small holes into a freestream have proven effective in the control of boundary layer separation. The beneficial effect of separation control is obtained only if the jets are pitched to the lower wall and skewed with respect to the freestream direction. In the previous study, the suppression effect of the orifice shape on flow separation was reported for three types of jet orifice (circular, triangular and square orifices). The triangular orifice generates the strong vortex and makes effective the pressure recovery in the diffuser in comparison with the circular and square orifices. In this study, four types of the jet orifice (model-U, model-D, model-R and model-L) are installed and the effect of the direction of the vertex of the triangular orifice on separation control is investigated in a two dimensional diffuser. Separation control is accomplished by all models, however the suppression of flow separation is most ineffective among the four models in the case of model-L (the vertex points to the direction of the jet pitch angle).