In design work, it is important to be cost-conscious. A skilled engineer can estimate production costs fairly accurately at the drawing stage. If a software-based estimation system could do the same, cost information could be obtained easily, facilitating cost-consciousness. In this study, an attempt was made to estimate component production costs from information in the drawings. The T-method(1) was employed. Although this method does not use information about correlations between items, we succeeded in improving the accuracy of the estimates by generating new items from such correlation information.