A variable polarized THz source employing a crossed-undulator configuration has been developed at Research Center for Electron Photon Science (ELPH), Tohoku University. An initial experiment will be demonstrated shortly using newly constructed compact planar undulators at a femtosecond short-bunch facility, t-ACTS, in ELPH. The undulators have equivalent parameters such as the period length of 8 cm and the number of periods is 7, but the field directions are crossed each other perpendicularly. The resonant frequency of 1.94 THz for the beam energy of 22 MeV. Magnetic field measurements have been already performed. The measured field strength distributions of the two undulators were mostly identical to each other. A beam transport line of variable R56 triple bend lattice intersecting the crossed-undulator configuration has been studied for phase control of interference between two radiations (namely the phase shifter). According to a tentative design of the phase shifter beam line, the degree of circular polarization may exceed 0.9 for the fundamental frequency of 1.94 THz in a narrow cone of angular spread of 2 mrad.