A camera is provided with an imaging element, and detects a timing of blinking of light which blinks periodically at a reference timing, based on a timing of variation in luminance of an image obtained by the imaging element, wherein the image is taken by the imaging element under a condition that the light blinks periodically at the reference timing. Further, the timing of exposure of the imaging element is adjusted based on the detected timing of the blinking light, thereby synchronizing shooting operations of plural cameras with each other.