To deliver an accurate alarm depending on the stage of fire by a constitution wherein a CCD TV camera processes a near infrared image having nonconstant radiation intensity generated from the flame of fire while discriminating from a constant near infrared image of other than fire.

A near infrared image picked up through a CCD TV camera is fed to a decision control circuit for discriminating the fire image where the image of solar beam or a fluorescent light is discriminated from the image of fire. The decision control circuit has a function for determining the projection area of fire image or the total sum of brightness at respective parts of fire image and measures the intensity of fire. Vertical and horizontal angles of tire are measured constantly along with the position thereof and the orientation and angle of camera are shifted by a measured angle thus imaging the fire in the center on the screen of TV camera at all times. Furthermore, a display control circuit superposes numerical information and image information on an inputted fire image and displays them visually. The image information is transmitted by a communication circuit to a central supervision room.