1. An adding metadata apparatus comprising: a first acquisition unit which acquires a first image, first metadata, and a first position within the first image, the first position being for displaying the first metadata; an extraction unit which extracts local features from the first image; a calculation unit which searches for a group of the local features within a predetermined distance from the first position, and calculates a representative point of the group; a search unit which matches the first image with a plurality of images stored in a database by using the local features, and searches for a second image which coincides with the local features; and a registration unit which calculates a second position, within the second image, corresponding to the representative point, and registers the second position and the first metadata as metadata for the second image.