To provide a device for acquiring an account balance-wise interest rate information which reduces the burden of a terminal operator by automatically processing an interest rate to be applied for a deposit account if any where the interest rate to be applied is changed in accordance with a balance.

A memory 6 as a first storage means where deposit balance data is stored together with time data and an interest rate data base 5 as a second storage means where interest data is stored as a data string corresponding to a period when pertinent interest is applied are provided, and interest data stored in the second storage means is corrected by deposit balance data stored in the first storage means, and corrected interest data is written in the first storage means in accordance with each deposit balance data corresponding to time data included in the period when pertinent interest data is applied.