A steer-by-wire steering system including a steering device (3) including a steering motor (35) and a controller (5) configured to supply a steering current to the steering motor (35) based on a steering request. The controller (5) includes a plurality of calculating portions (51, 54, 57), a plurality of drive circuits (52, 55, 58), and a plurality of temperature sensors (53, 56, 59). When a detection temperature difference that is a difference between detection temperatures of any two of the plurality of temperature sensors (53, 56, 59) is greater than a predetermined threshold, each of the plurality of calculating portions (51, 54, 57) executes an independent calculation control to independently calculate and set a current limit value, which is an upper limit value of the steering current, based on a detection temperature of one of the plurality of temperature sensors (53, 56, 59) corresponding to itself, irrespective of detection temperatures of one or more of the plurality of temperature sensors (53, 56, 59) other than the one of the plurality of temperature sensors (53, 56, 59) corresponding to itself.