A portable device search system for an electronic key system is formed by a portable device and handy equipment such as a cellular phone, PDA and the like, which is separate from the portable device. When a predetermined operation is performed on the handy equipment, the handy equipment transmits a search signal. On receiving the search signal, the portable device generates a specific sound and vibration to notify the location. In addition, an image near the portable device may be transmitted to the handy equipment to be displayed on the handy equipment.