A phase shifter can prevent a coupling phenomenon from being generated between a rotation line and the other line by controlling the dielectric constant of dielectric layers. The dielectric substrate(200) is made of the dielectric material having the first dielectric constant. The ground plate is formed in the lower part of the dielectric substrate. The first dielectric layer(202) comprises the first sub dielectric layer(202A) having the second dielectric constant and the second sub dielectric layers(202B) having the third dielectric constant. The first dielectric layer is arranged between the first line(206) and the axis of rotation(210) in the range of rotation of the longitudinal axis arm for the phase change.
