The invention relates to a reverse rotation-preventing device for a fishing reel by improving a reverse rotation-preventing function in real fishing by preventing unnecessary slip of a reverse rotation-preventing body. This reverse rotation-preventing device for the fishing reel has the reverse rotation-preventing body connected to a rotor synchronously rotating with a handle operation through a one-way clutch, and an engaging member capable of being engaged with an engaging part for preventing the reverse rotation, installed in the reverse rotation-preventing body in the periphery direction. The engaging part is constituted of engaging parts for reverse rotation, capable of engaging with the engaging member when the reverse rotation-preventing body is rotated in the reverse direction, and engaging parts for normal rotation, having sizes nearly equal to or more than those of the engaging parts for the reverse rotation, protruded in the radius direction, and capable of engaging with the engaging member when the reverse rotation- preventing body rotates normally. |