A conformational analysis of ethylene oxide and methylene chains for the mixtures of nonionic surfactant (polyethyleneglycol mono n-dodecyl ether, C12EOn, n = 5 similar to 8) with pure water was carried out by FT-Raman spectroscopy measurements to clarify the relationship between the conformation of the methylene or ethylene oxide chain and the aggregate for C12EOn in the pure water. The trans conformation for C-C bond in the hydrophilic ethylene oxide chain in liquid crystalline phase was less than that in aqueous micellar solution and pure C12EOn. On the other hand, the order of the hydrophobic methylene chain decreased with increasing concentration of C12EOn.