1. A digital pictorial book system for searching for and providing a user with an explanation of an object captured by an image capturing sensor, the digital pictorial book system comprising: an image capturing sensor for capturing an image; a display that displays the image captured by the image capturing sensor; a main object selecting means for selecting a main object out of the image; a feature extracting means for extracting a feature of the main object; an explanation searching means for searching for an explanation of the main object in a plurality of image databases, which store explanations of objects corresponding to a plurality of different kinds of features of the objects by using the feature extracted by said feature extracting means; and a distinguishing feature selecting means for selecting a distinguishing feature, of which an overlap of certainty distributions is the smallest for each object and each kind of the feature out of the different kinds of features stored in the plurality of image databases corresponding to the plurality of objects in case the explanations of the plurality of objects are searched out by said explanation searching means, wherein the distinguishing feature is the feature having a largest probability difference between a probability of a quantity of the feature extracted by said feature extracting means existing in an object corresponding to one of the plurality of explanations searched out by said explanation searching means and a highest probability among probabilities of the quantity of the feature extracted by said feature extracting means existing in other objects corresponding to the plurality of explanations searched out by said explanation searching means.