There is provided a control method for an information terminal device having a display and controlling an air conditioner over a network. The control method makes the information terminal device perform processing including: displaying a temperature setting screen where an air conditioner temperature is settable for each of a plurality of time periods; calculating a first time period preset temperature using a first preset temperature at a boundary time and a second preset temperature at a go-to-bed time; calculating a second time period preset temperature using the first preset temperature and a third preset temperature at a wake-up time; displaying the first time period preset temperature and second time period preset temperature; and outputting to the network a control command corresponding to the first preset temperature and second preset temperature when the first time period preset temperature and second time period preset temperature have been fixed.