The person involved stripped a magnetis bar unit whose weight was approximately 14 kilogram from the magnetic cobbing machine after filling drums with powder product NA-11F. He talk over a matter of the unit with his boss since he found that more powder is adherent to it than usual. Letting it down 2.4 meter on the floor, they checked and cleaned it in detail. Afert that, when he mounted the ladder holding it on his right, he fell off the ladder.