The steagy shear and viscoelastic behaviors of polyaniline suspension in the mineral oil subject to an electric field were studied experimentally using a Couette cell type rheometer. The dynamic yield stress determined from the plateau stress in the range of low shear rate was evaluated as a function of the applied field and particle volume fraction. The resultant yield stress is linearly increased with volume fraction and E. The storage shear modulus and loss modulus have been measured using small amplitude forced oscillatory dynamic test as functions of strain amplitude, driving frequency, and the applied field strength. The linear viscoelastic region was found to be as below 0.01 of strain amplitude by performing the amplitude sweep test. The storage and loss moduli were strongly dependent upon strain amplitude while those were nearly independent of the driving frequency for the range of 10∼10rad/s.