To provide an ash separator and an ash separation method which can reduce energy costs by separating ash contained in carbon ash and recovering unburned carbon efficiently, and recycle coal ash from which the unburned carbon is separated/removed, as, for example, a secondary material for concrete, and a unburned carbon separation method using the ash separation method.

The ash separator is a device for separating ash contained in coal ash, and has an ultrasonic trough with ultrasonic vibrators, a plurality of rolls disposed in the trough so as to be rotatable and impressed with voltage, and scrapers disposed on the upper surfaces of a plurality of the rolls and scraping ash adhering onto the surfaces of the rolls. The unburned carbon separation method uses the ash separation method.