An electric power steering apparatus that driving-controls a three-phase brushless motor which applies an assist torque to a steering mechanism of a vehicle by using a current command value calculated based on at least a steering torque, and vector-controls said three-phase brushless motor by using dq-axes command values that are converted from said current command value via an inverter, characterized in that said electric power steering apparatus comprising: a three-phase disturbance observer to compensate respective phase disturbance voltages, which include a dead time of said inverter, for 3-phase voltage command values, wherein said 3-phase disturbance observer includes phase observer sections comprising a motor model (100u,100v,100w), an inverse motor model (228u,228v,228w) and a low pass filter (226u,226v,226w) for each of three phases, and wherein said phase observer sections comprise: a first subtracting section (221u,221v,221w) to subtract a disturbance estimation voltage from a phase voltage that is converted into three phases; a gain section (222u,22v,222w) to multiply a subtraction value from said first subtracting section (221u,221v,221w) by a gain; said motor model (100u,100v,100w) to input a phase voltage that adds a disturbance element to an output of said gain section (222u,22v,222w), and to output a phase current; said inverse motor model (228u,228v,228w) to input said phase current; said low pass filter (226u,226v,226w) to input said subtraction value; and a second subtracting section (227u,227v,227w) to subtract an output of said low pass filter (226u,226v,226w) from an output of said inverse motor model (228u,228v,228w), and to output said disturbance estimation voltage. a three-phase disturbance observer to compensate respective phase disturbance voltages, which include a dead time of said inverter, for 3-phase voltage command values, wherein said 3-phase disturbance observer includes phase observer sections comprising a motor model (100u,100v,100w), an inverse motor model (228u,228v,228w) and a low pass filter (226u,226v,226w) for each of three phases, and wherein said phase observer sections comprise: a first subtracting section (221u,221v,221w) to subtract a disturbance estimation voltage from a phase voltage that is converted into three phases; a gain section (222u,22v,222w) to multiply a subtraction value from said first subtracting section (221u,221v,221w) by a gain; said motor model (100u,100v,100w) to input a phase voltage that adds a disturbance element to an output of said gain section (222u,22v,222w), and to output a phase current; said inverse motor model (228u,228v,228w) to input said phase current; said low pass filter (226u,226v,226w) to input said subtraction value; and a second subtracting section (227u,227v,227w) to subtract an output of said low pass filter (226u,226v,226w) from an output of said inverse motor model (228u,228v,228w), and to output said disturbance estimation voltage. a first subtracting section (221u,221v,221w) to subtract a disturbance estimation voltage from a phase voltage that is converted into three phases; a gain section (222u,22v,222w) to multiply a subtraction value from said first subtracting section (221u,221v,221w) by a gain; said motor model (100u,100v,100w) to input a phase voltage that adds a disturbance element to an output of said gain section (222u,22v,222w), and to output a phase current; said inverse motor model (228u,228v,228w) to input said phase current; said low pass filter (226u,226v,226w) to input said subtraction value; and a second subtracting section (227u,227v,227w) to subtract an output of said low pass filter (226u,226v,226w) from an output of said inverse motor model (228u,228v,228w), and to output said disturbance estimation voltage.