An enumeration plan generation unit 81 generates a set of logical formula structures each representing a way of combining logical formula expressions each representing a combination of features by use of the features of learning data items and the maximum number of features to be combined, and generates partial logical formula structures by dividing a logical formula expression included in each of the generated logical formula structures into two, and generates an enumeration plan in which the partial logical formula structures are linked to the logical formula structure from which the partial logical formula structures are divided. The feature generation unit 82 generates a new feature that is a combination of the features corresponding to the generated partial logical formula structures. Furthermore, the enumeration plan generation unit 81 divides the logical formula structure into two such that the numbers of the features included in the two partial logical formula structures generated from each of the logical formula structures are substantially equal.