A liquid-level detecting apparatus is provided. The liquid-level detecting apparatus includes a resistance plate with an insulating substrate; conductive segments on the insulating substrate at substantially equal intervals; a resistor mounted on the conductive segments and through which the conductive segments are connected to each other; an conductive sliding arm including a contact part for selectively coming into sliding contact with a portion of the conductive segments; a conducting pattern which is formed between one or more pairs of two adjacent conductive segments to short-circuit the two adjacent conductive segments; and a measuring device which is connected to one of the conductive segments and measures a value based on a portion of the resistor connected between a first segment of the conductive segments contacted by the contact part and the one of the conductive segments connected to the measuring device, thereby detecting a level of the liquid surface.