PURPOSE: The raw material for bast fiber is subjected to drafting, opening, and pressing, then sent to the skin scraper which is composed of a specially structured grind-scraping drum, a guide bed and a conveying bed and to a pair of suction drums to remove contaminants such rubber effectively.

CONSTITUTION: The raw material for bast fiber such as fax is cut into a prescribed length, beaten, kneaded. Then, it is sent to the drafting part 2 consisting of rollers 3,4 with conveyor 1 where drafting, opening and press-loosening are effected. Further, it is sent to the skin scraper 5 where hard contaminants firmly sticking to the fiber such as gum or pectin are ground off and removed. This device is composed of the grinding drum 6 with saw-edge-like projections 20 on the peripheral surface, the arc-shaped guide bed 7 with a plurality of slits 11 along the lower half of the drum surface and the horizontal conveying bed 8. The resultant bast fiber 17 is sent to a pair of vertically set sucking drums 13 to remove hard components and contaminants remaining in the fiber.