An information terminal control method includes: (a) predicting whether an amount of power consumption in a shop exceeds a target value; (b) when the amount of power consumption in the shop is predicted to exceed the target value, causing a display of an information terminal to display a screen displaying a time period during which the amount of power consumption in the shop is predicted to exceed the target value; and (c) causing the display to display a screen displaying a message that presents an action to reduce the amount of power consumption in the time period.