An image acquiring device for a sheet-type medium includes an upper passage plate and a lower passage plate, a gap being reserved between the upper passage plate and the lower passage plate to form a passage; at least two driving wheels mounted on the lower passage plate, and configured to drive the sheet-type medium entered into the passage to advance along the direction of the passage; at least two floating pinch rollers mounted on the upper passage plate, and each being mounted cooperatively with a respective driving wheel and being tangent to the driving wheel at a tangential point, and being configured to apply a pressure to the sheet-type medium to allow the sheet-type medium to cling to the driving wheel; and an image collecting device, mounted between two sets of the driving wheels and the floating pinch rollers, and configured to collect an image of the sheet-type medium.