A drafting device (6) includes a back roller pair (14), a third roller pair (15), a middle roller pair (16), and a front roller pair (17) that draft a fiber bundle (F). The drafting device (6) also includes a stepping motor that rotationally drives a back bottom roller (14a) of the back roller pair (14), a main control device (5a) that receives setting of a drafting condition about the fiber bundle (F), and a unit control device (10) that controls an operation of the stepping motor. The unit control device (10) adjusts the operation of the stepping motor such that the drafting performed by the roller pairs (14, 15, 16, 17) is within a range that satisfies the drafting condition received by the main control device (5a).