A toner includes a plurality of toner particles each having a core and a shell layer residing on a surface of the core. Each of the toner particles has a distribution of surface potential, as measured by a scanning probe microscope with respect to a 1 μm2 region of the toner particle in a state where no external additive adheres thereto, satisfying that the surface potential is at least Vmin+ΔV×0.4 in at least 70% and no greater than 95% of the 1 μm2 region, where ΔV denotes a potential difference calculated by subtracting a minimum surface potential Vmin of the 1 μm2 region from a maximum surface potential Vmax of the 1 μm2 region.