Documentation techniques are developing day by day. However, a practical system requires a higher cost performance level and its design is very difficult. This paper introduces a patent information control system developed by the Central Research Laboratories, Nippon Electric Co., Ltd. This system is a total system having 1) a microfilm system, 2) a card retrieval system and (3) a computer ritrieval system. Herein, we describe the system design and an outline of system and explain details of the card retrieval system.