Proton-terminated polystyrene-block-poly(4-vinylpyridine) (P(St-b-4VP)-H) and 3,3,3-trifluoropropyldimethylsilane-terminated polystyrene-block-poly(4-vinylpyridine) (P(St-b-4VP)-C2CF) symmetric diblock copolymers were synthesized by a living anionic polymerization. Differential scanning calorimetry (DSC) measurements revealed that both diblock copolymers were in a microphase-separated state in the bulk. The results of X-ray photoelectron spectroscopy (XPS) measurements revealed that in the case of the P(St-b-4VP)-H film, the surface weight fraction of poly(4-vinylpyridine) (P4VP) decreased drastically on annealing at 432 K for 90 h in order to minimize the magnitude of the free energy at the air-polymer interface, whereas in the case of the P(St-b-4VP)-C2CF film, the surface P4VP weight fraction was almost the same as the bulk value even after annealing at 423 K for 90 h. Also, scanning force microscopy observations (SFM) were in good agreement with the XPS results. These results clearly indicate that the surface molecular aggregation state of the hydrophobic-hydrophilic diblock copolymer film can be controlled by the hydrophobicity of the chain end groups.