PROBLEM TO BE SOLVED: To provide a production device which can obtain wide opened fibers suitable as production materials for absorbers for sanitary materials such as disposable diapers.SOLUTION: A preliminary fiber-opening unit 1, a fiber-opening unit 2, an expanding/shaping unit 3 and an addition part unit 4 form a communicating space for continuously feeding a fiber tow 10. The fiber tow 10 is opened in fiber-opening zones Zand Z, expanded and shaped in the expanding/shaping unit 3, and added with water absorbent.