Modulation instability of two-dimensional plane wave are investigated in competing cubic-quintic nonlinear media with fourth order diffraction (FOD). Growth rate of modulation instability are obtained analytically with linear-stability analysis. Besides main band, another side band of instability spectra appears in some regions of anomalous FOD. Normal FOD promote, while anomalous FOD and competing self-defocusing quintic nonlinearity always suppress modulation instability. Analytical results are also verified numerically by employing split-step Fourier transform method.