Polycavemoside A (1) has been isolated as one of the sources of human intoxication from the red alga Polycavernosa tsudai by Yasumoto et al. in 1993. They have proposed the planar structure of 1, which is a novel macrolide disaccharide, on the basis of ^1H and ^<13>C NMR spectra. However, although the respective relative configurations of the tetrahydrofuran ring, the tetrahydropyran ring, and the sugar moieties have been clarified, the absolute configuration of the whole molecule has not been established yet. We have started the total synthesis of this compound, because of its unusual molecular structure, the significant toxic activity, and the lack of a satisfactory natural source. We describe herein the construction of tetrahydrofuran ring segment 5, tetrahydropyran ring segment 6, and model compound 41 corresponding to the disaccharide segment 4. The synthesis of 5 was accomplished using Sharpless epoxidation reaction and Evans alkylation reaction as key steps. The stereoselective construction of tetrahydropyran ring of 6 was achieved by the intramolecular Michael reaction of (Z-α, β-unsaturated ester diol 32 which was synthesized from (S)-glycidol as starting material. Disaccharide 41 was conveniently synthesized from L-fucose and D-xylose. Further studies toward the total synthesis of 1 are now in progress.