This paper shows that different amounts of hydrogen are absorbed into polycrystalline silicon (Poly-Si) film depending on its Structures such as oxide film under Poly-Si film and metallization pattern on Poly-Si film. We examined how hydrogen affected the conductive mechanism of Poly-Si film, and measured the absorption of hydrogen into Poly-Si film by elastic recoil detection analysis (ERDA). Our investigations revealed that the change in Poly-Si film resistance was caused by a decrease in trap density, which occurred when dangling bonds were filled with hydrogen. This hydrogen was due to diffusion of hydrogen in plasma-enhanced chemical-vapor-deposited silicon nitride (P-SiN) film. It was confirmed that the absorption of hydrogen was the cause of the decrease in resistance using ERDA.