A method of the present disclosure causes a computer of an information apparatus to: display a display screen which specifies each of two or more illumination devices including a first illumination device; when selection of the first illumination device is detected, display a first room screen, either with brightness not lower than predetermined brightness or with brightness lower than the predetermined brightness; output to the network a first control command for turning off power of the first illumination device when selection inside a region of the first room screen is detected while the first room screen is being displayed with brightness not lower than the predetermined brightness; and output to the network a second control command for turning on power of the first illumination device when selection inside the region is detected while the first room screen is being displayed with brightness lower than the predetermined brightness.