A reciprocating mechanism (6) includes a worm shaft (21) with a helical groove (21a) and a sliding member (22). The worm shaft (21) is disposed parallel to a spool shaft (15). The sliding member (22) moves back-and-forth along an axial direction of the spool shaft (15) by rotation of the worm shaft (21). The sliding member (22) includes a body member (22a) with a recess portion (22d) having an engaging member (22b). The engaging member (22b) includes an engaging portion (70), a first shaft portion (71) and a second shaft portion (72). The engaging portion (70) engages with the helical groove (21 a). The first shaft portion (71) is formed on an end portion adjacent the engaging portion (70) to have a diameter smaller than a diameter of the engaging portion (70). The second shaft portion (72) is formed on an end portion of the first shaft portion (71) that is remote from the engaging portion (70) to have a diameter smaller than a diameter of the first shaft portion (71).
