Longitudinal (streamwise) vortices are produced by the interaction between jets and a free-stream. The fluid particles which have large energy of the freestream are supplied to decelerated fluid particles in the boundary layer by longitudinal vortices. The vortex generator jets can adjust the strength of longitudinal vortices by varying the jet speed. Therefore, they can achieve the adaptive control by properly adjusting the jet speed corresponding to flow parameters such as the angle of attack of an airfoil, the diffuser's divergence angle. In this study, the suppression effect of the shape of orifice of vortex generator jets on flow separation is investigated for three types of jet orifice (circular, triangle and square orifices). The triangle orifice generates the strong vorticity of longitudinal vortices and effective the pressure recovery in the diffuser in comparison with the other orifice shapes. Furthermore, the orifice shape of vortex generator jets causes the different tendency of the pressure recovery in the downstream direction.