We report on a study of carbon thirteen (13C) NMR spectra in a superconducting fulleride K3C60. It is found that the spectra are reproduced as powder patterns of anisotropic NMR shifts. By analyzing the NMR shifts, the ratio of isotropic hyperfine coupling (Aisospin) of conduction electrons to anisotropic one (Aaxspin) is obtained experimentally for the first time (Aisospin/Aaxspin = 0.78). The substantial isotropy is consistent with the crystal structure of the C60 molecule. The contribution of carbon pπ-orbitals to Aaxspin is found to be dominant.
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