To provide a delivery failure detecting device for a paper sheet printer capable of detecting delivery failure in a wide range around a delivery base for stacking paper sheets and thereby preventing damage of components such as a detecting piece.

This device is equipped with a first detecting piece of which one end is rotatably supported with respect to a guide means protruding almost in parallel to the delivery base over the paper sheets stacked on the delivery base, a second detecting piece provided in a direction cutting off a peripheral turning path of a feeding means for feeding the paper sheets and rotatably supported, and a detector for detecting rotational conditions of the first and the second detecting pieces. The rotational directions of the first and the second detection pieces are the directions apart from the peripheral turning path of the feeding means for feeding the paper sheets.