A device for preventing fishing line backlash in a double-bearing type fishing reel wherein a spool is loaded by magnetic induction to prevent the backlash. The device is so constructed that magnet rings are located inside and outside of an electric conductive ring fixed to a spool shaft. One of the magnetic rings is rotated by an adjusting disc having a guide slot to engage a lug on the rotated ring to adjust the magnetic induction brake force for the spool.