An acceleration sensor includes a fixation member, a weight member including a plate with two opposing sides parallel or substantially parallel to an X-direction and two opposing sides parallel to a Y-axis direction in a plan view, the weight member including a cutout extending in a direction about 45° relative to the X and Y axis directions, a vibrating beam linearly extending in the direction about 45° relative to the X and Y axis directions in the plan view, and one end portion is connected to the fixation member and the other end portion is connected to the weight member, the vibrating beam is partly arranged within the cutout and supporting the weight member to be displaceable in a Z-axis direction, a driver disposed on the vibrating beam and vibrating the vibrating beam, and a detector disposed on the vibrating beam and outputting a detection signal that is changed depending on deformation of the vibrating beam.