A financial instrument called a reverse mortgage is provided without any client' s risk by a method comprising a step of virtually determining the applied interests, discount rates, and real estate prices at a death time and at a financing time in a simulation and calculating the expectation of the present value on the payer' s side from the determined applied interests, discount rates, and real estate prices, a step of calculating an assumed settlement money at a virtual settlement time and calculating the expectation of the present value of the recipient' s side by taking the smaller one out of the assumed settlement money and the real estate price, and a step of determining a premium such that the present value of the payer' s side is equal to that of the recipient' s side.