The invention provides a scale detection method and a scale detection device for a water boiling utensil. The scale detection method comprises the steps as follows: obtaining the total energy consumption for heating water in the water boiling utensil to a designated temperature; calculating the unit energy consumption for heating the unit quantity of water to the designated temperature by the water boiling utensil according to the total energy consumption and the water quantity in the water boiling utensil; when the unit energy consumption is larger than or equal to a predetermined value, judging that scale exists in the water boiling utensil. By the aid of the scale detection method and the scale detection device, the scale in the water boiling utensil can be detected accurately, so that whether the scale is required to be removed or not can be judged accurately.