A fly reel spool rotatably coupled with a frame mounted on a fishing rod to wind a fish line includes a rotary frame rotatably coupled inside the frame； a winding drum having a ball-catching protrusion on an inner circumference coupling with the rotary frame, the winding drum configured such that the fish line is wound on or unwound from an outer circumference； a locking ball installed in an outer circumference of the rotary frame to protrude from and retract into the rotary frame； elastic means for elastically holding the locking ball so that it protrudes from the outer circumference of the rotary frame, whereby the locking ball is caught by one touch on the ball-catching protrusion on the inner circumference of the winding drum when the rotary frame is coupled with the winding drum, and stopping means for supporting the winding drum and the rotary frame to rotate together.
