We have been operating an infrared Stokes spectro-polarimeter, whose observing wavelength bands include the He I 10830 and Fe I 15648 lines. A couple of full-Sun, full-Stokes maps in both wavelength bands are taken on a daily basis, with the polarization sensitivity better than 10^-3. With this sensitivity, the helium polarization maps clearly show the atomic and Hanle polarization besides the Zeeman polarization, particularly in prominences/filaments. On these polarization maps, we can track the magnetic field signals of the prominences/filaments during their passages on the solar disk. Therefore, this instrument works as a "synoptic prominence magnetograph". In the conference, we show some examples of the polarimetric data of the prominences/filaments (both quiescent and eventually erupted ones).