According to one embodiment, a pick up device for paper sheets includes an input unit configured to support a plurality of paper sheets in a stacked manner, a supply mechanism configured to move the placed paper sheets in a stacking direction and supply each paper sheet to an pick up position, a pick up mechanism configured to pick up the paper sheet at the pick up position from the input unit one by one, and a control unit configured to determine a supply speed or a feed amount of the paper sheets by the supply mechanism in accordance with thickness information per unit time of the picked up paper sheets obtained from a thickness detector, and configured to determine whether the supply mechanism is to be operated or stopped based on density information of the paper sheets obtained from a paper sheet sensor.