Lipid membrane dynamics in cell sized vesicles (CSVs) in water is characterized by the solution-state NMR. CSV is successfully prepared by natural swelling method using osmotic effect. Broad 1 H NMR signal and large 31 P NMR chemical shift anisotropy show the slow tumbling of the lipid with the rotational correlation time 0.2–2.8s in CSV of 10–20μm-diameters. The 1 H– 1 H nuclear Overhauser effect enhancement reveals the proximity between the lipid headgroup and alkyl chains, in which the close distance, ∼0.4nm. The proximity is due to the large protrusion of the lipids in the vertical direction to the CSV surface.