Thin films of 5,5"’-bis(aminomethyl)-2,2’:5’,2 ":5 ",2"’-quaterthiophene, (1) and its dihydrochloride (2), both of which possess active amino groups at both the molecular terminals, have been fabricated by direct evaporation deposition. IR and XPS analyses have revealed that these thin films are deposited without causing chemical degradation during the course of deposition. Of these, the thin film of 1 is characterized by the molecular layered structure that can be noticed for the oligothiophene compounds widely, and in this structure the molecular long axis of 1 is nearly vertical to the substrate plane. On the other hand, the film of 2 turned out to be amorphous. The structure of 1 immediately means the presence of a densely packed array of the amino groups at the thin film surface. Making use of this structure, we tried surface modification of the thin film of 1 with an aldehyde. The resulting film was analyzed by XPS spectroscopy, and as a consequence, we confirmed that the surface modification is successfully achieved. Furthermore, we attempted immobilization of glucose oxidase (GOD) onto the thin film of 1 and examined its catalytic activity.