A spinning reel comprising: a reel body, a driving member rotatably supported on the reel body and including a pinion gear, the pinion gear being configured to be rotated by an operation of a handle of the spinning reel; a housing part that is fixed to the reel body and that includes an opening part, the housing part at least partially accommodating the driving member extending through a central opening of the opening part, a one-way clutch being located between the pinion gear and the housing part in the reel body; and a magnetic seal device being mounted to the opening part of the housing part, wherein the magnetic seal device seals a gap between the housing part and the pinion gear of the driving member at the opening part of the housing part; wherein the magnetic seal device comprises: a magnetic body being fitted to the pinion gear; a ring-shaped magnet being located radially outside of the magnetic body; a first magnetic plate and a second magnetic plate both having a ring shape and being disposed on axially opposite sides of the magnet, the first magnetic plate and the second magnetic plate being fixed to the housing part; and a magnetic fluid being disposed at a gap between the magnetic body and the first and second magnetic plates (9a, 9b), the magnetic fluid being maintained at the gap by magnetic force, wherein the first magnetic plate is provided closer to the one-way clutch compared with the second magnetic plate, said spinning reel being characterized in that the first magnetic plate has a larger outer diameter than the second magnetic plate. a reel body, a driving member rotatably supported on the reel body and including a pinion gear, the pinion gear being configured to be rotated by an operation of a handle of the spinning reel; a housing part that is fixed to the reel body and that includes an opening part, the housing part at least partially accommodating the driving member extending through a central opening of the opening part, a one-way clutch being located between the pinion gear and the housing part in the reel body; and a magnetic seal device being mounted to the opening part of the housing part, wherein the magnetic seal device seals a gap between the housing part and the pinion gear of the driving member at the opening part of the housing part; wherein the magnetic seal device comprises: a magnetic body being fitted to the pinion gear; a ring-shaped magnet being located radially outside of the magnetic body; a first magnetic plate and a second magnetic plate both having a ring shape and being disposed on axially opposite sides of the magnet, the first magnetic plate and the second magnetic plate being fixed to the housing part; and a magnetic fluid being disposed at a gap between the magnetic body and the first and second magnetic plates (9a, 9b), the magnetic fluid being maintained at the gap by magnetic force, a magnetic body being fitted to the pinion gear; a ring-shaped magnet being located radially outside of the magnetic body; a first magnetic plate and a second magnetic plate both having a ring shape and being disposed on axially opposite sides of the magnet, the first magnetic plate and the second magnetic plate being fixed to the housing part; and a magnetic fluid being disposed at a gap between the magnetic body and the first and second magnetic plates (9a, 9b), the magnetic fluid being maintained at the gap by magnetic force, wherein the first magnetic plate is provided closer to the one-way clutch compared with the second magnetic plate, said spinning reel being characterized in that the first magnetic plate has a larger outer diameter than the second magnetic plate.