An electric power steering apparatus having a function for detecting a steering speed, includes a time stamp attaching section that attaches a time stamp (ATi) to a detection signal (Ai) and attaches a time stamp (BTj) to a detection signal (Bj); a storing section that stores the detection signal (Bj) to which the time stamp (BTj) is attached; a synchronous signal searching section that searches the detection signal (Bj) most synchronized with the detection signal (Ai) based on the time stamps (ATi and BTj); a vernier calculating section that performs a calculation of an angle difference between synchronous signals searched by the synchronous signal searching section and a vernier calculation and outputs an absolute steering angle of a sensor reference; an initial steering angle calculating section that calculates an initial steering angle value from the absolute steering angle; and a steering angle output section that obtains a steering angle.