A floodlight section emits light with a predetermined blinking pattern. The emitted light is reflected by a reflecting object. An image capturing section captures the light reflected by the reflecting object. A surveillance apparatus compares the pattern of the reflected light captured by the image capturing section and the blinking pattern of the light emitted by the floodlight section to determine that there is no invader in a surveillance area between the surveillance apparatus and the reflecting object while the predetermined blinking pattern is detected, and that there is an invader in the surveillance area when the predetermined blinking pattern is not detected. The present invention can be applied to surveillance apparatuses.