An image sensing system is provided with a fluorescent lamp which performs AC lighting to irradiate an object, an inverter power source which supplies currents to the fluorescent lamp, a lighting frequency changing circuit which changes the frequency of the current supply, a lens which images an image onto a film, and a CCD image sensing device which is capable of changing the period of exposure by the formed image and which outputs the image of the object as an electric signal through photoelectric conversion. The exposure period of the CCD image sensing device is controlled by a microcomputer and a timing generator. The lighting frequency changing circuit is controlled so that the phase of the exposure period and the phase of the current supply to the fluorescent lamp are in synchronism with each other.