To make it possible to prevent surely the seizing of a bearing about a concrete compaction vibrator and simplify the maintenance of the vibrator dramatically.

On a rotary shaft 4, there is provided a central hole 8, which extends from the lower end to the height of a bearing along the shaft center while a branch hole 10 is provided, which distributes a lubricant to each of the bearings 2 and 3 from the central hole. The lubricant 9, which is housed to a position higher than the lower end of the rotary shaft 4 in the lower part inside an outer cylinder 1 is injected into the central hole 8 from the lower part of the outer cylinder 1 with a pump means 11 accompanied by the rotary motion of the rotary shaft 4.