A spinning reel (100) includes a handle (1), a reel unit (2), a rotor (3), a spool (4), a rotor drive mechanism (5), and an anti-reverse mechanism (50). The reel unit (2) has a fishing rod attachment portion (2b) and a mount portion (2e). The rotor drive mechanism (50) includes a drive gear (11) and a pinion gear (12). The pinion gear (12) is disposed in a through hole (2f) of the reel unit (2). The pinion gear (12) is meshed with the drive gear (11). The anti-reverse mechanism (50) is configured to prevent the rotor (3) from rotating in a fishing-line releasing direction. The anti-reverse mechanism (50) includes a one-way clutch assembly (51). The one-way clutch assembly (51) is detachably attached to the mount portion (2e) of the reel unit. The rotor drive mechanism (5) includes a seal member (16). The seal member (16) is configured to seal a clearance between the pinion gear (12) and the through hole (2f) while being disposed at a rear end of the one-way clutch assembly (51) in the back-and-forth direction.
