A fishing reel has a reel body and an adjusting device. The reel body has a spool that is made of metal. The adjusting device has an adjusting button, an adjusting base and a magnetic set. The adjusting button has an adjusting structure being spiral, facing the spool and forming a step between a highest part and a lowest part of the adjusting structure. The adjusting base has a coordinating portion being spiral, facing the adjusting structure and forming a step between a highest part and a lowest part of the coordinating portion. The magnet set is mounted on the adjusting base and faces the spool.