PURPOSE: To improve reliability and detection sensitivity, by monitoring an object to be detected with two detection means differing in sensitive wavelength region from each other and outputting an alarm signal when both detection means generate detection signals.

CONSTITUTION: Now, when a fire breaks out, an image pickup device picks up the image of the scene thereof and outputs a video signal which is fed to a marker generation detector 8. When the monitor position by the marker and the position coincide, the scene is projected on a monitor 6 and a detection signal is outputed. On the other hand, if the fire breaks out, the UV light from the fire is sensed by a sensor 19 and the change in a heat source is sensed by a comparator 21, the detection signal thereof is inputted to an output circuit 24. when both of the detection signal outputted when the video of the fire is detected and the detection signal outputted when the presence of the heat source is detected are fed to an output circuit 24, the circuit 24 outputs an alarm signal to a driving circuit 25, thereby giving an alarm and operating a fire extinguisher 27 or the like. The reliability is thus improved and the fire is detected with high sensitivity.