An electronic data management system for accurately determining the authenticity of the electronic data and the specification of the source of unauthenticated electronic data. A drawing output processor transmits original electronic drawing data A1 to an order receiving unit with a tag T attached. The order receiving unit and a manufacturing unit transmit a manufacturer's copied data B2(T) copied from the original data A1(T) to an inspection unit. The inspection unit transmits the inspection result Fa for the product M, the client's copied data A2 re-copied from the original data A1, and the manufacturer's copied data B2 (T) to a determination unit. The determination unit compares the tag T extracted from the manufacturer's copied data B2 with the original value of the client's copied data A2 and the original value of the manufacturer's copied data B2 and determines the authenticity of the client's copied data A2 and the manufacturer's copied data B2.