Abstract: This invention provides a plasma CVD method aimed at forming an amorphous silicon thin film on a large-area substrate at a high speed and also an apparatus therefor. The method and apparatus are characterized by a reaction vessel, means for feeding a reactant gas to the reaction vessel and discharging the same, discharging electrodes accommodated in the reaction vessel, a source for supplying power for glow discharge to the discharging electrodes, two pairs of solenoid coils arranged on opposite sides of said reaction vessel and so disposed that the axes thereof perpendicularly intersect each other as well as perpendicularly the electric field formed between the discharging electrodes, and an AC source for supplying power to said solenoid coils for magnetic field generation, whereby an amorphous silicon thin film is formed on a substrate held to intersect perpendicularly the electric field between the discharging electrodes.