A device for identifying consumable products including a main unit including an electronic circuit, and a consumable product detachably connected to the main unit. The consumable product includes a property-varying analog element whose analog value of electric property continuously varies when connected to the main unit and applied with a current. The main unit includes a current-applying portion for applying the current to the property-varying analog element of the consumable product, and a detecting portion for detecting the varying electric property of the property-varying analog element, which is applied with the current by the current-applying portion. With this device, in the state that the consumable product is connected to the main unit, the detecting portion of the main unit detects the time-varying electric property of the property-varying analog element of the consumable product, and identifies whether the consumable product is an authorized product or a substandard product based on the detected electric property.