A waterproof testing device tests waterproof performance of a waterproof component. The testing device includes an input unit, a storing unit and a determining unit. The input unit inputs permeability of one or more test objects with waterproof components disposed thereon and an air flow rate that is a volume of gas passing through the test object per unit time for each test object. The storing unit stores, in a data pair, the permeability and the air flow rate of each test object input by the input unit. The determining unit determines a range of permeability in which no water leakage occurs in the waterproof component based on a range of air flow rate in which no water leakage occurs and the stored permeability and air flow rate.