PURPOSE: To adjust only the phase between 0° and 180° by using a potential difference between a connecting point of a variable resistor and a capacitor of a series circuit comprising the variable resistor and the capacitor and a connecting point of two resistors of a series circuit comprising the two resistors having an identical resistance value as an output voltage.

CONSTITUTION: A series circuit of the variable resistor 2 and the capacitor 3 and the series circuit of the resistors 4, 5 having an identical resistance value are connected in parallel with an AC voltage signal source 1. Let a connecting point of the variable resistor 2 and the capacitor 3 be A and let a connecting point of the resistors 4, 5 be B, then a voltage VAB between the points A and B is equal to a half the voltage E of the power supply 1 regardless of adjustment of the variable resistor 2 and only the phase difference is adjusted between 0° and 180°. Thus, a phase shifter having a voltage being a half the voltage of the original signal and where only the phase difference is adjusted by 180° is constituted by adjusting the variable resistor.