A tooth whitening apparatus is an apparatus that whitens a tooth surface with light. The tooth whitening apparatus includes a sheet member attachable to the tooth surface, a color tone sensor disposed on the sheet member and detecting a color tone of a portion of the tooth surface adjacent to the color tone sensor, and a light-emitting device disposed at a position on the sheet member corresponding to a position at which the color tone sensor is disposed, the light-emitting device irradiating the portion of the tooth surface adjacent to the color tone sensor with the light in accordance with a detection result of the color tone sensor.
