A spool for a fishing reel is disclosed to include an axle, which has a surface and a recess curved inwards from the surface, two sidewalls radially extending from the two distal ends of the axle, and a pin, which is disposed in the recess with the topmost edge thereof kept in flush with the surface of the axle for the fastening of a fishing line for allowing the spool to take up or let off the fishing line smoothly.