A steering system comprising: a steered shaft supported on a housing so as to be reciprocally movable in an axial direction to steer steered wheels; a ball screw device that includes a rolling element screw portion in which an outer peripheral rolling groove is formed spirally in an outer peripheral surface of the steered shaft, a rolling element nut, in an inner peripheral surface of which an inner peripheral rolling groove corresponding to the outer peripheral rolling groove is formed, and a plurality of rolling elements rollably arranged in a rolling path formed between the outer peripheral rolling groove and the inner peripheral rolling groove; a motor that is fixed to the housing and that includes an output shaft offset from the steered shaft; a drive force transfer mechanism that includes a toothed drive pulley provided so as to be rotatable together with the output shaft, a toothed driven pulley provided integrally with the rolling element nut, and a toothed belt that transfers a drive force between the drive pulley and the driven pulley; and a rolling bearing disposed between the housing and the rolling element nut to support the rolling element nut so as to be rotatable relative to the housing, wherein: a first seal member that contacts an outer ring and an inner ring is provided on a side surface of the rolling bearing on a side of the driven pulley; characterized in that a second seal member that does not contact the outer ring or the inner ring is provided on a side surface of the rolling bearing on a side opposite to the side surface on the side of the driven pulley. a steered shaft supported on a housing so as to be reciprocally movable in an axial direction to steer steered wheels; a ball screw device that includes a rolling element screw portion in which an outer peripheral rolling groove is formed spirally in an outer peripheral surface of the steered shaft, a rolling element nut, in an inner peripheral surface of which an inner peripheral rolling groove corresponding to the outer peripheral rolling groove is formed, and a plurality of rolling elements rollably arranged in a rolling path formed between the outer peripheral rolling groove and the inner peripheral rolling groove; a motor that is fixed to the housing and that includes an output shaft offset from the steered shaft; a drive force transfer mechanism that includes a toothed drive pulley provided so as to be rotatable together with the output shaft, a toothed driven pulley provided integrally with the rolling element nut, and a toothed belt that transfers a drive force between the drive pulley and the driven pulley; and a rolling bearing disposed between the housing and the rolling element nut to support the rolling element nut so as to be rotatable relative to the housing, wherein: a first seal member that contacts an outer ring and an inner ring is provided on a side surface of the rolling bearing on a side of the driven pulley; characterized in that a second seal member that does not contact the outer ring or the inner ring is provided on a side surface of the rolling bearing on a side opposite to the side surface on the side of the driven pulley. a first seal member that contacts an outer ring and an inner ring is provided on a side surface of the rolling bearing on a side of the driven pulley; characterized in that a second seal member that does not contact the outer ring or the inner ring is provided on a side surface of the rolling bearing on a side opposite to the side surface on the side of the driven pulley.