To provide an evidence preservation system of a project for using recording regarding a construction state of a contractor as documentary evidence, which is suitably used when pursuing defect liability from a requester to the contractor.

The evidence preservation system of the project is provided with a drawing and specification management table 11 that receives drawings and specifications of an object of the project from a drawing and specification server 20, a project progress management table 12 in which progress states by every process are recorded, a project implementation history table 13 that records an implementation history of a contract agreement regarding the object of the project and an evidence management part 14 that manages preservation states of at least one of the drawing and specification table 11, the project progress management table 12 or the history of the object of the project recorded in the project implementation history table 13 as an evidence required for the defect liability or a claim for compensation regarding the object of the project.