In order to properly detect an outbreak of smoke using a photographic image, this detection device is equipped with an extraction unit, a calculation unit, and a detection unit. By using an image analysis result of an input image, that is, a photographic image captured of a scene under surveillance, the extraction unit generates an image for which a noise component is removed from the input image. By using brightness information contained in the generated image, the calculation unit calculates an attenuation factor of reflected light from a captured object in the input image. The detection unit determines whether an outbreak of smoke is present in the scene under surveillance based on the attenuation factor.