The asymptotic problem of a semi-infinite interface crack between dissimilar electrostrictive materials that are subjected to electric loading is numerically analyzed by using the finite element method. Numerical results of electric displacement fields are obtained on the basis of the mathematical equivalence of the mode III problem and an electrostatic problem. The shape and the size of saturation zones are explored as a function of the ratio of the saturated electric displacements of dissimilar electrostrictive materials. In contrast with conventional wisdom, the ratio of the permittivities is shown to exert a negligibly small influence on electric displacement fields. For various combinations of the material properties of dissimilar electrostrictive materials, stress fields and stress intensity factors are systemically calculated by using the numerical results of electric displacement fields. The effects of the electric, elastic, and electrostrictive properties on stress intensity factors are demonstrated.