Abstract: A market transaction automatic contracting system includes a market transaction automatic contracting apparatus (1) and transaction terminals (A, B . . . ) connected to the market transaction automatic contracting apparatus by communication circuits. The market transaction automatic contracting apparatus has a transaction conditions storage section (6) for storing transaction conditions set beforehand by participants, an offer/bid setting/distributing device (2) for reading offers (PrA, PrB . . .) and bids (PpA, PpB . . . ) made by the participants, and, with consideration to the transaction conditions, setting and distributing best offers (bPr) and best bids (bPp) most significant for each participant, an offer/bid match determining device (3) for determining whether a match occurred between an offer and a bid, and a contracting device (5) responsive to a match between an offer and a bid for concluding a transaction contract between the parties.