An information apparatus controlling method is provided. An instruction button for specifying a type of a target device that includes an illumination device and a floor plan representing each room in a building are displayed. A first room in the floor plan is displayed with brightness not lower than first brightness, when selection of the instruction button is detected and when a first illumination device in the first room is in an on-state. A first room screen corresponding to the first room is displayed with brightness not lower than second brightness, when selection of the first room is detected and when the first room is displayed with brightness not lower than the first brightness. A first control command is output to network for turning off power of the first illumination device in the first room, when selection within the first room screen is detected.