The present invention relates to a surveillance camera having a complex filtering-based autofocusing function robust to a change in a visibility state, and an image surveillance system having the sameapplied thereto, and comprises: a hardware filter for blocking one band among an infrared band and a visible light band of light, which has passed through a lens part, and allowing the other band totransmit therethrough; and a software filter for filtering a color image or a black-and-white image generated by an image signal processor (ISP) by removing an element, which reduces a visibility distance in front of the lens part, from the color image or the black-and-white image generated by the ISP, wherein: a filtering band of the hardware filter and whether to perform filtering by the software filter are controlled according to one filtering level corresponding to a current visibility state in front of the lens part among multiple filtering levels, so as to make it possible to provide animage clear enough to always allow identification of a target regardless of a visibility state in front of the surveillance camera; and autofocusing is performed using analysis of an image provided through step-by-step complex filtering, so as to make it possible to provide an always accurate autofocusing function regardless of the visibility state in front of the surveillance camera.