PROBLEM TO BE SOLVED : To provide a rent management device capable of motivating a real estate investor to invest real estate.SOLUTION : The rent management device for calculating and displaying a rent income of a real estate property for each specific unit time comprises an input acceptance unit for acquiring, from a user, a rent income per specific period of a real estate property and information about the rent income at a calculation start point of time of the rent income, specific unit time and current day and time, a first storage unit for storing the information, a computation unit for reading the information from the first storage unit to calculate a specific unit time rent income, calculate lapsed time, calculate an accumulated rent income and calculate the accumulated rent income every time the specific unit time elapses, and updating the accumulated rent income, a second storage unit for storing the specific unit time rent income, the lapsed time and the accumulated rent income, and an output unit for outputting the updated accumulated rent income.SELECTED DRAWING : Figure 6COPYRIGHT : (C)2019, JPO&INPIT