A content search device includes a feature quantity computing unit that computes a feature quantity of at least any one of an image feature, an acoustic feature and a semantic feature included in each piece of content data, and that stores feature quantity data. The device also includes an unknown feature quantity computing unit that computes an unknown feature quantity of each feature type not associated with a content identifier in the feature quantity data by use of the feature quantity of the feature type associated with the content identifier, and that stores the unknown feature quantity as a feature estimated value in the feature quantity data. The device further includes a distance computing unit that computes a distance indicating a similarity between each two pieces of content data based on the feature quantities and the feature estimated values stored in the feature quantity data. The device still further includes a display unit that determines a display position of a thumbnail corresponding to each piece of content data based on the distances computed by the distance computing unit, and that displays the thumbnail on a display device.