A semiconductor acceleration sensor in which a reduction in size can be achieved when electrodes are formed in a chip main body and acceleration can be measured with good sensitivity. The semiconductor acceleration sensor comprises a weight section, flexible sections which support the weight section and have measurement elements P, and a chip main body which has a front surface having chip electrodes electrically connected with the measurement elements, and support the flexible sections, wherein an additional weight, which has an inclined face which surrounds a bonding section and decreases its size toward the bonding section, is bonded on the front surface of the weight section.