There is provided an electric power steering system that is able to generate a more appropriate current command value. Limits of an assist controlled variable, formed of multiple upper limits and multiple lower limits are individually set for multiple signals used to compute the assist controlled variable. The values obtained by adding the limits together are set as final limits of the assist controlled variable, that is, an upper limit and a lower limit. Thus, even if the assist controlled variable exhibiting an abnormal value is computed for some reason, the abnormal value of the assist controlled variable is limited to an appropriate value corresponding to each signal value by the final limits. By supplying the appropriate assist controlled variable to a motor control signal generating unit as a final current command value, an appropriate assist force is applied to a steering system.