Abstract: A discharge defect detecting device including a sensor that reads image, which has been formed on a medium by moving nozzles relative to the medium in a relative movement direction and discharging a fluid, at a reading resolution lower than the resolution of an image data in the relative movement direction, based on the image data; a standard data forming unit that forms a standard data having the same resolution as the reading resolution in the relative movement direction, based on the image data; and a detecting unit that compares a plurality of the reading data pixels on the same row in the relative movement direction in the data read by the sensor with a plurality of standard data pixels each corresponding to the plurality of the reading data pixels in the standard data, to detect the discharge defects of the nozzles.