A portable accessory for preventing death grip of a hand-held apparatus and improving radio wave transmission and reception of the hand-held apparatus. The portable accessory includes an inductive signal amplifying circuit including: a radio transmission/radio unit that transmits or receives radio waves; a capacitive coupled unit that is capacitively coupled with an antenna mounted in the hand-held apparatus; and an impedance matching unit that connects the radio wave transmission/reception unit and the capacitive coupled unit and transmits radio waves.