Abstract: A highly accelerated stress test device includes: a first heater that heats a test space; a second heater that heats a steam generating space; a first sensor that measures a first temperature of the test space; a second sensor that measures a second temperature of the steam generating space; an item temperature sensor that is directly attached to a sample placed in the test space and that measures an item temperature of the sample; and a controller that prepares, as candidates for a test mode, a normal mode in which on-off control of each of the first and second heaters is carried out based on the first and second temperatures, and an item-temperature mode in which the on-off control is carried out based on the item and second temperatures, and carries out the on-off control according to the test mode that is set with a test condition of the sample.