An indication displayed by a display unit included in a pressure switch is inverted and the respective setting functions of push-button switches are reversed when the operator is obliged to look at the display unit from a direction opposite a normal looking direction or when the pressure switch is installed in an inverted position. A mode setting push-button switch 113 is operated to turn the indication indicating a set pressure displayed by a display unit 116 through an angle of 180.degree., a function to increase the set pressure of a first push-button switch 111 is reversed and a function to decrease the set pressure of the second push-button switch 112 is reversed.