A real estate network market system comprises the calculation of a reasonable price range and yield, which are presented to a seller and a prospective buyer. In the event that the maximum desired buying price presented by the buyer is lower than the desired selling price, and the difference is higher than an adjustment rate, both parties shall revise their prices until the desired selling price and the maximum desired buying price are in equilibrium. If the difference is within the adjustment rate, the average of the desired selling price and the maximum buying price is presented to the seller and the prospective buyer who presented the maximum desired buying price, and thereby adjusted by the market company. A virtual building is created on a network, the market data is integrated, the equilibrium price is determined, and an index pertaining to investment real estate is produced.