We report a colossal resistance drop around insulator-metal transition temperature (T_MI) in Sm0.55Sr0.45MnO₃ induced by direct current. Polycrystalline samples of Sm 0.55Sr0.45MnO₃ were synthesized through solid state reaction method. They have been investigated by X-ray diffraction for phase evaluation, scanning electron microscopy for grain morphology and dc resistivity measurement techniques for resistivity-temperature behavior. The resistivity-temperature behavior has been measured with different biasing currents (1 mA, 2.5 mA, 5 mA, 10 mA and 50 mA). With increasing biasing current, the resistivity of the samples decreased drastically. The change in the resistivity of the samples for bias currents 1 mA and 50 mA at T_MI was found to be ~2560%. This phenomenon of electroresistance is discussed in view of strong interaction between carrier spins and localized spins in Mn ions and percolative mechanism of phase-separation.