A rapidly oscillating Ap star pulsates in high-order p-modes under the influence of a strong magnetic field. The strong field distorts spatially the angluar and the radial pulsation amplitude (eigenfunction). To study the effect of the magnetic field on the radiative excitation and the damping of p-modes, we performed a fully nonadiabatic analysis including the effect of a dipole magnetic field. A magnetic field always tends to stabilize low order p-modes. In the presence of a magnetic field stronger than $\sim 1{\rm kG}$, all $\delta$ Scuti type pulsations are stabilized. For high-order p-modes, on the other hand, the magnetic field enhances $\kappa$-mechanism excitation in some range of the field strength, depending on the pulsation frequency.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html