To prevent a single bidder from profiting by submitting multiple false-name bids, an auctioneer: sets a threshold price r; determines the ranking i of the minimum value equal to or larger than r in a buyers' evaluation value sequence sorted in decreasing order and the ranking j of the maximum value equal to or smaller than r in a sellers' evaluation value sequence sorted in increasing order; if i=j, allows first to i-th buyers and sellers to trade at the price r; if i>j, allows first to j-th buyers and sellers to trade at a trade price of the (j+1)-th buyer's evaluation value for the buyers and at the threshold price r for the sellers; and if i