We present Raman and infrared studies on the structures of organic semiconductor thin films used for electronic devices. The Raman spectra of crystalline and amorphous states of an organic semiconductor, N,N′-di-1-naphthaleyl-N,N′-diphenyl-1,1′-biphenyl-4, 4′-diamine (NPD), were measured. These states give rise to slightly different peak positions and widths of each Raman band. Raman images were observed for polycrystalline pentacene films evaporated on a silicon substrate. The structural defects were found in the images of the intensity ratio I 1596/I1533, which reflects the orientation of molecules i.e., crystalline domains. Photoinduced infrared absorption from the composite of regioregular poly(3-dodecylthiphene) and C60 was measured by the difference FT-IR method. The observed absorption is attributable to photogenerated carriers. The action spectra of photoinduced infrared absorption are explained by electron transfer from photogenerated excited states on a polymer chain to C60.