A barrel plating or high-speed rotary plating method for electronic components, and a neutral tin plating solution used therein. A plating solution that includes (A) stannous ions, (B) an acid or a salt, (C) a complexing agent, and (D) a diamine that has a polyoxyalkylene chain, and that has a pH in a range between 4 and 8 is used. The use of this neutral tin plating solution prevents the electronic components from coupling together during the barrel plating, enabling an improvement in manufacturability in barrel plating.