A pressure sensor includes a sensor body which has a first surface and a cavity with an opening in the first surface, a cantilever which has a base end portion supported on the first surface and a distal end portion provided to form a gap from a peripheral edge of the opening inside the opening, is flexurally deformed according to a pressure difference between an inside and an outside of the cavity, and is formed of a semiconductor material, and a displacement measurement unit which measures a displacement of the cantilever vibrating according to the pressure difference at a frequency larger than a lower limit frequency f LOW (Hz) defined by Expression (1), where a width (µm) of the gap is represented by G, a volume (ml) of the cavity is represented by V, and a proportional constant is represented by k. f LOW = k ⋅ G 2 / V