Piezoelectric potential of a InN nanowire (NW) growing along [01 (1) over bar0] can be positive, negative, and zero depending on the direction of the applied transverse force. By measuring the output voltage of a InN-NW-based nanogenerator, about 40% to 55% of output voltages are within the range of -1 and -20 mV, and 25% to 30% of output voltages would exceed -100 mV. Some output voltages could reach the magnitude of -1000 mV, showing its great potential for fabricating high-output nanogenerators.