In manufacturing a crystalline silicon-based solar cell having an intrinsic silicon-based thin film and a conductive silicon-based thin film in this order on a conductive single-crystalline silicon substrate, plasma treatment is performed after the intrinsic silicon-based thin film is formed on the conductive single-crystalline silicon substrate. In the plasma treatment, a surface of the intrinsic silicon-based thin film is exposed to hydrogen plasma while a hydrogen gas and silicon-containing gases are being introduced into a CVD chamber. The amount of the hydrogen introduced into the CVD chamber during the plasma treatment is 150 to 2500 times the introduction amount of the silicon-containing gases.