The present invention relates to a credit card payment method and a real estate cash receipt issuing method when buying and selling real estate, and a payment system brokerage system which allows a credit card payment when buying, selling, and leasing real estate and paying real estate utility bills by using a brokerage system. Even if a lessee intends to pay a monthly rent by a credit card, a lessor could not accept a credit card payment if the lessor is an individual or the lessor is not a card member store or does not own a payment device even if the lessor has a lease business registration number. The National Tax Service which is a related organization encourages a lease business to accept credit card payments, but credit card payments are not accepted by the same reason. The present invention carries out payments by an online brokerage system to make credit card payments for sales expenses, lease expenses, and management expenses for real estate, and provides an online brokerage system construction method for carrying out issuance of related proof data and real estate cash receipts.(110) Lease transaction management unit(120) Short term lease transaction management unit(130) Real estate transaction management unit(140) Utility bill information management unit(150) General sales transaction management unit(160) Online contract management unit(170) Document management unit(180) Payment processing unit(AA) Brokerage systemCOPYRIGHT KIPO 2017