An acceleration sensor having a support frame, a weight supported within the support frame via flexible beams, semiconductor piezoresistance elements provided on the beams, and wiring interconnecting the piezoresistance elements. The acceleration sensor detects acceleration from changes in resistance of the piezoresistance elements. Stress damping sections are provided on those portions of the beams which exclude the portions where the piezoresistance elements are provided. Each stress damping section is symmetrical with respect to the point of intersection between the length center line of the beam and the width center line of the beam.