A method for manufacturing a bearing device includes steps: providing a hollow mold, then injecting a feedstock of powder and molten binder into the mold under pressure, thus forming a desired perform of a cylindrical body and a desired perform of a cover; separating the binder from the desired perform of the body and the desired perform of the cover; sintering the desired perform of the body and the desired perform of the cover, thereby forming the body and the cover; and mounting the cover on the body, thereby forming the bearing device.