A light-shielding agent and a film-forming composition containing it, which prevent separation of formulation surfaces or powder floating phenomenon, which are caused by irradiation by light or ultraviolet light, improve luster of formulation surfaces, maintain external appearance of formulations, and do not impair stability or quality of pharmaceutical preparations, or the like, are provided. The light-shielding agent includes a calcium-containing compound, and the film-forming composition includes the light-shielding agent including the calcium-containing compound and a film-forming base agent. The present invention also provides a formulation and a capsule, which are coated with both or either of the above-mentioned light-shielding agent and/or the above-mentioned film-forming composition.