A touch panel apparatus for measuring biosignals and a method of measuring the biosignals by using the touch panel apparatus, are provided. The touch panel apparatus includes a first electrode array configured to detect touch input signals, a second electrode array configured to be coupled to the first electrode array based on driving power, a controller configured to determine an operation mode of the touch panel apparatus as either a manipulation mode configured to manipulate a screen of the touch panel apparatus or a measuring mode configured to measure the biosignals, based on the detected touch input signals, and a mode converter configured to connect the second electrode array to a source of the driving power in response to the controller determining the operation mode as the manipulation mode, and connect the second electrode array to ground in response to the controller determining the operation mode as the measuring mode.