A device for measuring voltage, including a voltage detecting portion for detecting a plurality of voltages and outputting a maximum voltage of the plurality of voltages, a voltage latching portion that receives a first output from the voltage detecting portion, and a voltage reading portion that receives a second output from the voltage latching portion. Another device for measuring voltage, including a supply voltage, a ground voltage, and first and second supply voltage measuring units connected in parallel to each other between the supply voltage and the ground voltage. A method for measuring voltage, including receiving a plurality of voltages, detecting a maximum voltage from the plurality of voltages, maintaining the detected maximum voltage, and outputting the maintained detected maximum voltage.