Apparatus for continuously producing semiconductor films on substrates in a vacuum chamber. A plurality of reaction chambers are provided within the vacuum chamber, substrates are supported by a top plate and transferred to each reaction chamber, which are filled with a certain reactant gas mixture while the substrates are heated from above the reaction chamber. Continuous treatment of the substrates is provided with an increase in reactant gas utilization efficiency. Disturbance of reactant gas flow by thermal convection is prevented and semiconductor layers having smooth surfaces are formed.