Effects of plate angle on acoustic waves from a supersonic jet impinging on an inclined flat plate with its angle of 30, 45 and 60 degrees are numerically investigated. Threedimensional compressible Navier-Stokes equations are solved with the modified weighted compact nonlinear scheme. The acoustic fields indicate that there are at least three kinds of acoustic waves in all the cases considered similar to previous studies: (i) Mach waves generated from the shear layer of the main jet, (ii) acoustic waves generated from the impingement region, (iii) Mach waves generated from the shear layer of the supersonic flow downstream of the jet impingement. Acoustic waves (ii) are generated from two different acoustic sources; one is interaction between plate shock and shear layer, and the other is interaction between bubble-induced shock and shear layer. The freauency characteristics of acoustic waves are related to the thickness of shear layer at the impinging region. The results in this study show the source location and characteristics of acoustic wave (ii) for the cases with the various flat plate angles.