Provided are a golf ball which has a surface that sparkles when exposed to ultraviolet rays even if a naturally derived substance is used as a fluorescent material, and it is environmentally and human friendly, and a resin composition for a cover or a topcoat therefor. A resin composition for a cover or a topcoat of a golf ball of the present invention includes: a resin for a cover or a topcoat; and a plant-derived or alga-derived extract which emits light using an absorbed light as an energy source, as a fluorescent material. In the golf ball of the present invention, the cover or the topcoat is formed by using such a resin composition.