A power steering device includes a bearing configured to rotatably support the tip side of a worm shaft, the gear case housing the worm shaft and a holder housed in a housing hole provided in the gear case and configured to house the second bearing. The holder includes the first holder having a holding part configured to hold the outer periphery of the bearing and the opening part configured to expose a part of the outer periphery of the bearing, the second holder having a guide part configured to guide a movement of the bearing toward a worm wheel as the outer periphery of the bearing comes into contact with the guide part through the opening part and a spring configured to bias the bearing toward the worm wheel via the first holder.