An oscillating mechanism includes a traverse camshaft, an engaging unit, and a slider body. The traverse camshaft includes a spiral groove. The traverse camshaft rotates in conjunction with the winding operation of a handle attached to the reel main body. The engaging unit includes an engaging claw configured to engage the spiral groove. The slider body includes a supporting hole rotatably supporting the engaging unit. A groove extends in the penetration direction of the supporting hole, and is disposed on the inner peripheral surface of the supporting hole of the slider body.