A drafting device adapted to draft a fiber bundle, the draft device comprising: plural drafting rollers (14A, 15A, 16A, 17A, 14B, 15B, 16B, 17B) arranged successively in a direction in which the fiber bundle is conveyed, the drafting rollers (14A, 15A, 16A, 17A, 14B, 15B, 16B, 17B) being arranged as plural roller pairs (14, 15, 16, 17), each roller pair (14, 15, 16, 17) having a top roller (14B, 15B, 16B, 17B) and a bottom roller (14A, 15A, 16A, 17A) opposing the top roller (14B, 15B, 16B, 17B); a supporting member (61; 14D, 15D, 16D, 17D; 71; 117) adapted to support the drafting rollers (14A, 15A, 16A, 17A, 14B, 15B, 16B, 17B); and a resonance preventing structure (95; 96; 14D, 15D, 16D, 17D; 100; 71; 117A, 117B; 109) adapted to prevent occurrence of resonance between the drafting rollers (14A, 15A, 16A, 17A, 14B, 15B, 16B, 17B) and the supporting member (61; 14D, 15D, 16D, 17D; 71; 117) that may be caused by rotation of the drafting rollers (14A, 15A, 16A, 17A, 14B, 15B, 16B, 17B) wherein the supporting member includes a cradle adapted to rotatably support the top rollers (14B, 15B, 16B, 17B), characterized in that the cradle has a lateral face that is formed by applying bending processing to a plate-like member and extending between a top face of the cradle and an attachment part of the cradle, wherein supporting structures supporting the supporting member (61; 14D, 15D, 16D, 17D; 71; 117) are fixed to the attachment part, and the resonance preventing structure is at least one of a rib that is formed in a region including a section to which the bending processing is applied, and first reinforcing parts each of which is formed by processing the lateral face and each of which extends in a direction intersecting axial directions of the top rollers (14B, 15B, 16B, 17B) and a direction in which the roller pairs (14, 15, 16, 17) are arranged, the first reinforcing parts being arranged side by side along the direction in which the roller pairs (14, 15, 16, 17) are arranged. plural drafting rollers (14A, 15A, 16A, 17A, 14B, 15B, 16B, 17B) arranged successively in a direction in which the fiber bundle is conveyed, the drafting rollers (14A, 15A, 16A, 17A, 14B, 15B, 16B, 17B) being arranged as plural roller pairs (14, 15, 16, 17), each roller pair (14, 15, 16, 17) having a top roller (14B, 15B, 16B, 17B) and a bottom roller (14A, 15A, 16A, 17A) opposing the top roller (14B, 15B, 16B, 17B); a supporting member (61; 14D, 15D, 16D, 17D; 71; 117) adapted to support the drafting rollers (14A, 15A, 16A, 17A, 14B, 15B, 16B, 17B); and a resonance preventing structure (95; 96; 14D, 15D, 16D, 17D; 100; 71; 117A, 117B; 109) adapted to prevent occurrence of resonance between the drafting rollers (14A, 15A, 16A, 17A, 14B, 15B, 16B, 17B) and the supporting member (61; 14D, 15D, 16D, 17D; 71; 117) that may be caused by rotation of the drafting rollers (14A, 15A, 16A, 17A, 14B, 15B, 16B, 17B) wherein the supporting member includes a cradle adapted to rotatably support the top rollers (14B, 15B, 16B, 17B), characterized in that wherein the supporting member includes a cradle adapted to rotatably support the top rollers (14B, 15B, 16B, 17B), characterized in that the cradle has a lateral face that is formed by applying bending processing to a plate-like member and extending between a top face of the cradle and an attachment part of the cradle, wherein supporting structures supporting the supporting member (61; 14D, 15D, 16D, 17D; 71; 117) are fixed to the attachment part, and the resonance preventing structure is at least one of a rib that is formed in a region including a section to which the bending processing is applied, and first reinforcing parts each of which is formed by processing the lateral face and each of which extends in a direction intersecting axial directions of the top rollers (14B, 15B, 16B, 17B) and a direction in which the roller pairs (14, 15, 16, 17) are arranged, the first reinforcing parts being arranged side by side along the direction in which the roller pairs (14, 15, 16, 17) are arranged. a rib that is formed in a region including a section to which the bending processing is applied, and first reinforcing parts each of which is formed by processing the lateral face and each of which extends in a direction intersecting axial directions of the top rollers (14B, 15B, 16B, 17B) and a direction in which the roller pairs (14, 15, 16, 17) are arranged, the first reinforcing parts being arranged side by side along the direction in which the roller pairs (14, 15, 16, 17) are arranged.