In a portable terminal system having a portable terminal device and an external speaker 6 for converting electrical signals from the portable terminal device to electrical signals, the portable terminal device 21 and the external speaker portion 19 are equipped with first and second connectors 20, 2, and by electrically connecting the first and second connectors, the electrical signals from the portable terminal device are transmitted to the external speaker 6. The first connector 20 and the external speaker 6 are provided with transmission holes 18, 8 for transmitting to the portable terminal device side the sound wave signal converted on the basis of the electrical signals by the external speaker 6.