To provide an acceleration sensor chip for an inexpensive semiconductor acceleration sensor, which can perform acceleration detection simply, accurately and stably without the effect of strong capacitance.

A silicon substrate 100 having a movable electrode part 100a and a beam part 100b, which is also used as a weight, has the silicon diaphragm structure, wherein a low-resistance epitaxial layer part 100X containing high- concentration impurities and a silicon substrate part 100Y having the reverse- type concentration with respect to the part 100X are laminated. In this case, the beam part 100b is formed by the etching stopping at a P-N junction plane MP-N between the epitaxial layer part 100X and the silicon substrate part 100Y. In the meantime, thin-film contact parts 41 and 42 are formed on the edge parts of conductor pattern parts 71 and 72 for connecting external conductive connecting members provided on step parts 20a and 30a of a pair of insulating substrates 20 and 30, which are bonded to the upper and lower sides of the silicon substrate 100. The electric contact by any of the thin-film contact parts 41 and 42 and the silicon substrate 100 is obtained when acceleration is applied.