To provide a design support system which can enhance reusability of historical data about past design work and improve work efficiency, design work history data is divided according to an instruction to generate unit work history data, input work made by a person in charge of work in a history is retrieved, input of design support information for the work is accepted, and the input design support information is inserted into the unit work history data to be stored in a database 1. The person in charge of work who reuses the unit work history data performs design work with reference to the design work history data which is previously reproduced in a design support window shown on a display section 24 of a design support device 2 and the design support information contained in it.