Pressure measuring apparatus

To provide a portable pressure measuring apparatus with a pressure sensor of highly accurate output and small electric power consumption. A pressure measuring apparatus of the invention is provided with an impedance bridge circuit (pressure sensor part) for measuring pressure; a drive unit (sensor driving part) for applying voltage to the above impedance bridge circuit; a measuring unit (voltmeter) for sampling and measuring the electric potential difference between the middle points in both arms of the above impedance bridge circuit at a fixed time interval; and a determining unit (control part) for determining whether the difference between the pressure this time and the previous pressure sampled and measured by the above measuring unit reaches a predetermined threshold or below.