A spool braking device for a dual-bearing reel that applies a braking force to a spool during casting includes a spool brake unit, a switch element, a casting state detecting device and a spool control device. The spool brake unit is configured to brake the spool and includes a rotor having a plurality of magnets and a plurality of coils. The magnets are arranged along a rotational direction with alternating polarities. The coils are arranged to be spaced apart in a circumferential direction. The coils have end faces that are arranged to face a side face of the rotor. Each of the coils has a winding diameter that is larger than a full length of the coil. The casting state detecting device is configured to detect a casting state. The spool control device is configured to control an on/off status of the switch element based on the casting state.