1. An image searching system comprising: an image database storing a plurality of database images to be searched for; a specifying controller for specifying a plurality of key images used to specify search conditions; an extracting controller for extracting common feature values of common images from the plural key images specified by the specifying controller; a calculating controller for comparing the common feature values, extracted by the extracting controller, with the feature values of the plural database images to thereby sequentially calculate similarities between the common feature values and the database image feature values; and a searching controller for retrieving from the database images one of the images which is similar to the key image, based on a similarity calculated by the calculating controller.