Abstract: Disclosed is a pressure gauge which is mainly composed of two parts, a pressure sensing element and an electronic processing and displaying unit. The pressure sensing element includes an elastic member and a variable resistor whose resistance value can be varied by the force of the pressure. An output electrical signal is occasioned by the electronic circuit, which is in proportions corresponding to the resistance value of the variable resistor. The electronic processing and displaying unit will further process the output electrical signal and display the value of the pressure in an indicator, preferably a liquid crystal display (LCD). The pressure goes through a calibration process every time when the power is just turned on to calibrate an initial output electrical signal occasioned by the variable resistor.