A rack shaft has a rolling contact surface on the opposite side of rack teeth across an axis line X, and a pair of slanted surfaces extending in parallel with the axis line across the rolling contact surface. Furthermore, a roller rolling on the rolling contact surface of the rack shaft and an urging member having contact with the pair of slanted surfaces for applying an urging force are provided. The urging member is attached to the housing, forms an annular configuration surrounding the entire circumference of the rack shaft, and has contact portions having contact with the pair of slanted surfaces to apply the urging force.