Carbon nanotubes were suspended in carbon tetrachloride and placed in magnetic fields of < 80.0 kOe at 310 K. Scanning electron microscopy showed that a single and free nanotube was oriented with the tube axis parallel to the fields. From the Boltzmann distribution of tube directions, the anisotropy of susceptibilities parallel (chi (parallel to)) and perpendicular (chi (perpendicular to)) to the tube axis is estimated to be chi (parallel to) - chi (perpendicular to) similar to (9 +/- 5) x 10(-6) emu per mole of carbon atoms (chi (perpendicular to) < chi (parallel to) < 0).