An acceleration sensor includes a weight portion having a recess section and a solid section, beam portions, a movable electrode provided on the opposite surface of the weight portion from an open surface of the recess section to extend over the recess section and the solid section, a first fixed electrode arranged at the opposite side of the movable electrode from the recess section, and a second fixed electrode arranged at the opposite side of the movable electrode from the solid section. The acceleration sensor detects acceleration using a change in capacitance between the movable electrode and the fixed electrodes caused by rotation of the weight portion. The beam portions are shifted toward the recess section such that an angle between a perpendicular line extending from a gravity center position of the weight portion to the rotation axis and a surface of the movable electrode becomes equal to 45 degrees.