In a digital camera system used by connecting it to a computer or the like, a still image can be stored by acting upon a release button of the camera. To this end, a card-type digital camera used by connecting it to a personal computer is provided with the release button for controlling the connected personal computer, an actuation of this release button being processed by software running on a CPU of the personal computer. The release button of the camera may be used to have a desired function by providing a function selecting unit of application software.