Provided is a positively-chargeable toner for developing electrostatic images excellent in printing durability, charge stability, and conveyance amount stability. The toner comprises colored resin particles comprising a binder resin and a colorant, and an external additive, wherein the external additive comprises spherical silica particles with a number average particle diameter of 70 to 200 nm. wherein the external additive has a particle size distribution in which a percentage of a number of particles having a particle diameter of 50 nm or more is 75% or more, which is calculated based on a SEM image.