Resin particles include mother particles containing a biodegradable resin, in which an alkali metal atomic weight A present on a resin particle surface with respect to a total atomic weight present on the resin particle surface, which is measured by an X-ray photoelectron spectroscopy, and an alkali metal atomic weight B present in the resin particles with respect to the total atomic weight present on the resin particles, which is measured by a fluorescent X-ray spectroscopy, satisfy a relationship of 0≤(A/B)