A camera includes an image sensor, a storing module, an infrared shutter module, and a controlling module. The image sensor converts light rays projected thereon to digital image signals. The storing module is for storing the digital image signals. The infrared shutter module includes an infrared emitter and an infrared receiver adjacent to the infrared emitter, and when infrared rays emitted from the infrared emitter are transmitted into the infrared receiver, the infrared shutter module outputs a triggering signal. The controlling module electrically connects to the image sensor, the storing module, the infrared shutter module and stores the digital image signals in the storing module when receiving the triggering signal.