<p>A vibration sensor according to the present invention includes a piezoelectric vibrator including a diaphragm and a piezoelectric element firmly fixed to at least one plane surface of the diaphragm and a signal process substrate performing a predetermined process to a signal outputted from the piezoelectric vibrator, and wherein the piezoelectric vibrator and the signal process substrate are arranged alongside in a planar direction nearly perpendicular to a vibration direction of the piezoelectric vibrator.</p>
