Disclosed herein is an inertial sensor including: a membrane; first and second driving units provided in a first axis direction (an X axis direction) so as to be symmetrical to each other based on a predetermined point of the membrane to thereby vibrate while being expanded and contracted in the first axis direction; and third and fourth driving units provided in a second axis direction (a Y axis direction) perpendicular to the first axis direction so as to be symmetrical to each other based on a predetermined point of the membrane to thereby vibrate while being expanded and contracted in the second axis direction, wherein the first and second driving units have different vibration frequencies so that they vibrate while being expanded and contracted in the opposite manner and then vibrate while being expanded and contracted in the same manner.