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Abstract. Medium-resolution (R 15 000) circular spectropolarimetry of T Tauri is presented. The star was observed twice: on November 11, 1996 and January 22, 2002. Weak circular polarization was found in photospheric absorption lines, indicating a mean surface longitudinal magnetic field B of 160 ± 40 G and 140 ± 50 G at the epoch of the first and second observations respectively. While these values are near the detection limit of our apparatus, we belive that they are real. One can conclude from our data that B of T Tau does not significantly exceed 200 G, which is much less than surface magnetic field strength of the star (>2.3 kG) found by Guenther et al. (1999) and Johns-Krull et al. (2000). We discuss possible reasons for this difference.

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It is shown that the existence of hot accretion spots at the surface of T Tau practically has no effect on the accuracy of estimation of its magnetic field strength at photospheric level.We also found that one can interpret results of T Tau's photospheric magnetic field strength measurements carried out via different methods in the frame of the following alternative: 1) if T Tau's inclination angle i ≤ 10 • , then magnetic field of the star may be dipolar with the angle between rotational and magnetic axes is near 85 • ; 2) if it will be found (e.g. from interferometric observations) that i > 10 • , then magnetic field of T Tau is essentially non-dipolar or/and non-stationary.

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