PURPOSE: To provide a capacitive pressure sensor designed to improve the linearity of output characteristics while the pressure sensitivity is set high in a required state.

CONSTITUTION: A silicon substrate 10 with a diaphragm 13 and a flat glass substrate 11 are united by anodic bonding. A pressure introduction path 17 is formed to penetrate the glass substrate up and down, making it possible to supply a measuring pressure P to a pressure chamber 14. A pressure leak groove 18 is formed at a predetermined position of a bonding face of the silicon substrate at the side bonded to the glass substrate. Accordingly, a part of the measuring pressure is let to leak outside through the pressure leak groove. The leaking amount is determined by a correlation of a cross sectional area S2 of the leak groove and an area S1 of the pressure introduction path. A ratio of the leaking amount to the supplying amount of gas decreases in accordance with an increase of the pressure. Since the ratio of the leaking amount is non-linear, the non-linearity of the deflecting amount of the diaphragm to the pressure is offset, thus widening an area of the linearity.