Disclosed is a pressure sensor which can achieve both a larger capacitance change and miniaturization of a device than ever before. A pressure sensor comprises a layer constitution in which a dielectric layer is sandwiched by a pair of electrode layers and a pair of insulating substrates in order, and detects pressure based on a capacitance value between electrodes which is varied by a deflection amount of at least one of the dielectric layer and the pair of the electrode layers and, wherein, on each side of the pressure sensor, at least one of the electrode layer and the dielectric layer has concave and convex parts on the surface facing the other layer, and the electrode layer and the dielectric layer are in contact with each other through at least the convex parts of the concave and convex parts.