A product trading system has a production information accumulating means for accumulating production information of a product produced by each of mobile production machines under the seller's administration, a demand information accepting means for accepting demand information about the product which the seller would like to purchase, a matching processing means for performing a matching processing that derives optimal production information from the production information being accumulated in the production information accumulation means in consideration of freight cost based on the demand information accepted at the demand information accepting means, and a matching processing result presentation means for representing the buyer the processing results from the matching processing means.