Block copolymers containing polystyrene, poly(4-octylatyrene), or polyisoprene as a hydrophobic segment and poly(2,3-dihydroxypropyl methacrylate) (poly(DIMA)) as a hydrophilic segment have been synthesized by anionic living polymerization. Microphase-separated structures of the block copolymers, poly(styrene-b-DIMA), poly(4-octylstyrene-b-DIMA), and poly(isoprene-b-DIMA), were confirmed by small-angle X-ray scattering and transmission electron microscopic (TEM) observation. Angle-dependent X-ray photoelectron spectroscopic (XPS) measurement of the as-cast film surfaces of the three block copolymers clearly indicated enrichment of the hydrophobic segments in the outermost surfaces. Furthermore, the XPS measurements revealed that the poly(DIMA) segment was enriched in the surface of poly(styrene-b-DIMA) soaked in water and that reconstruction of the surface occurred again by annealing the sample in air. The cross-sectional TEM view of poly(styrene-b-DIMA) film showed that the top surface was almost covered with a polystyrene layer for the as-cast film and that the spherical polystyrene domains were wrapped with a poly(DIMA) domain on the surface of the film soaked in water. Contact angle measurement indicated enrichment of the hydrophobic segment in the as-cast film surfaces of the three block copolymers and reconstruction of the surface structures according to dry and wet conditions.