A determination assistance device includes an infrared image acquirer that acquires an infrared image by imaging an area including an air outlet of an air conditioner, a communicator that communicates with the air conditioner, an inputter that accepts data inputs, imaging switch operations, and the like performed by user, a display that displays image data and the like, a controller that controls overall operations of the determination assistance, and a storage that stores various data, a program, and the like. A display controller of the controller displays on the display the infrared image and whether or not abnormality, determined by the infrared image, is present in the air conditioner.