Complete assignments of the cross-polarization/magic-angle spinning (CP/MAS) C-13 nuclear magnetic resonance (NMR) spectrum of the cellulose I-ethylenediamine (EDA) complex, which is the intermediate of the reaction from cellulose I to cellulose III1, were performed. In this paper, we used the (13) C-enriched cellulose that was biosynthesized by Acetobacter xylinum ATCC10245 strain from culture medium containing D-(2-C-13), D-(3-C-13), or D-(5-C-13)glucose as a carbon source. After conversion into cellulose I-EDA complex by sufficient EDA treatment, the CP/MAS C-13 NMR spectra of the C-13-enriched cellulose I-EDA complexes were measured. As a result, C-11 resonance lines of each carbon of the cellulose moiety in the complex appeared as a singlet, suggesting that all glucose residues of the complex are magnetically equivalent. The difference in chemical shifts for each carbon between cellulose I-EDA and cellulose I-alpha, I-beta, and IIII, respectively, suggests that the conformation of the cellulose chains for cellulose I-EDA differs from that for cellulose Ialpha, Ibeta, and III1. In addition, fitting analysis of the C-13 spectrum of Valonia cellulose I-EDA complex revealed that the complex contains one EDA molecule per two glucose residues in the cellulose chain.