A reciprocating mechanism (31) for a fishing reel (1) includes a first rotating body (37), a second rotating body (39), a rotation transmission body (41) and a movable body (43). The first rotating body (37) is configured to rotate in conjunction with a winding operation of a handle (13) of the fishing reel (1). The second rotating body (39) is arranged spaced apart from the first rotating body (37) along a spool shaft (17) direction in which the spool shaft (17) of the fishing reel (1) extends. The rotation transmission body (41) is bridged between the first rotating body (37) and the second rotating body (39), and is configured to transmit the rotation of the first rotating body (37) to the second rotating body (39). The movable body (43) is configured to engage the rotation transmission body (41), and is configured to reciprocate in the spool shaft (17) direction accompanying an actuation of the rotation transmission body (41).本發明之目的在於提供一種能夠實現在與捲筒軸正交之方向上之小型化的往復移動機構。本擺動機構31具備第1皮帶輪37、第2皮帶輪39、皮帶41、及滑件43。第1皮帶輪37與握柄13之捲取操作連動而旋轉。第2皮帶輪39沿軸向與第1皮帶輪37隔以間隔而配置。皮帶41架設於第1皮帶輪37及第2皮帶輪39之間，而將第1皮帶輪37之旋轉傳遞至第2皮帶輪39。滑件43與皮帶41卡合，並伴隨著皮帶41之作動而在軸向上往復移動。
