To facilitate work in spite of being under a pressure reduced atmosphere, by ensuring impregnation of a lubricating liquid to a porous bearing material, by maximally eliminating labor for removing the lubricating liquid, by minimizing sticking of the lubricating liquid of a bearing holder external part.

The inside of a vacuum constant temperature bath V is reduced in pressure, and the inside of a housing 16 including a void of a bearing sleeve 18 is exhausted and reduced in pressure. A support frame S is lowered, and an opening side part of a bearing structure 12 is soaked in oil L, to be blocked up. The oil L permeates into the void of the bearing sleeve 18. When the inside of the vacuum constant temperature bath V is recovered to the pressure, the oil L rises, and the oil L is sufficiently impregnated into the bearing sleeve 18. Afterwards, the support frame S is lifted, and the oil L is impregnated into the bearing sleeve 18 by releasing blocking-up by the oil L of an opening part of the bearing structure 12, and a lubricating liquid impregnated porous bearing body of flowing down excessive oil of a bearing hole 18b is provided.