A grip-strength device with detection function comprises: a grip-strength assembly comprising a first supporting piece, a second supporting piece, a rebounding element, a plurality of detection elements, a circuit element, a pull-force measuring element, and a power-supply element. The user can hold the grip-strength assembly and press the first supporting piece and the second supporting piece; and the force given by the user to the first supporting piece and the second supporting piece is measured by the pull-force measuring element; thereby detecting the user's grip force; or touching the detection elements with both hands, the circuit element will generate the detection current to enter the human body through the detection elements and then returns to the circuit element to detect the muscle mass in the human body; thereby the grip-strength assembly can have the functions of simultaneously detecting the grip strength and the body's muscle mass.