An acceleration sensor is based on a semiconductor technique which is suitable for mass production. The resulting acceleration sensor is small in size and high in precision. The acceleration sensor includes a stationary section, an acting section to which a force is applied in response to acceleration, a flexible section through which the stationary section is coupled to the acting section, a plurality of distortion sensing elements coupled to the flexible section, a first weight having a bottomed hole which is gradually smaller in width towards the bottom of the hole, the first weight being coupled to the acting section and a second weight, greater in specific gravity than the first weight, coupled to the bottom of the hole of the first weight.