Abstract: A generating device to supply electricity to a monitoring device of abnormal state of tire at a lower cost for a long time. The generating device includes a single pendulum 4, a hammer 6 supported at a point S? on the circumference of a wheel 2, a spring 7 joining the single pendulum 4 and the hammer 6 by soft join, piezoceramics 8a and 8b converting distortion generated by the vibration adding force from the hammer 6 into a form of electricity, and cushion members 9a and 9b holding the positions of the piezoceramics 8a and 8b. A single pendulum 2 has vibrational frequency as same as or of integral multiplication of the rotational frequency of a tire 1.