Аннотация:Results are presented for narrow-band (resolutions of 50 and 100 A) and broadband UBVJK photometry as well as polarization observations of the R CrB variable SU Tau. The observed polarization is found to be mainly interstellar in origin, the interstellar absorption is estimated to be about 1.3 to 2.0 magnitudes, and an absolute visual magnitude of -3 is obtained, which is characteristic of R CrB-type stars. The continuum of SU Tau near maximum light is shown to correspond to a supergiant of spectral type not later than G1. An IR excess in the spectral region from 1.25 to 2.2 microns is detected which corresponds to blackbody emission from dust with a temperature of about 1000 K. The luminosity decline is attributed to the screening effect of a cloud of graphite particles having a radius of the order of 0.06 micron. It is noted that reddening is greatest during the stage of luminosity rise, which is also characteristic of other R CrB-type stars.