To provide a method for crushing an inorganic fiber material by continuously feeding the inorganic fiber material between a pair of rolls rotated in mutually opposite directions and crushing the fed inorganic fiber material by the press force of the rolls, capable of continuously and efficiently crushing the inorganic fiber material such as glass wool and controlling the glass fibers contained in the obtained crushed product in a desired shape.

This method for crushing an inorganic fiber material such as glass wool comprises crushing the glass wool between a pair of a main roll 3 and the first sub-roll 4 and subsequently feeding the obtained coarsely crushed glass wool between the other pair of the main roll 3 and the second sub-roll 4' rotated in the arrow direction. When passing between the rolls 3, 4', the fed coarsely crushed glass wool again receives a press force. The coarsely crushed pieces insufficiently crushed between the first pair of the rolls 3, 4 are thereby sufficiently crushed. A clearance between the rolls 3, 4' is maintained at a distance of 0.1-1.0 mm without relating to the METSUKE of the crushed glass wool, and the aspect ratio of the crushed fibers can thereby be controlled to 6-125.