Abstract: An effusion cell assembly for epitaxial apparatus is disclosed. The assembly includes an effusion cell incluing a growing material, a heater for supplying heats with the effusion cell to effuse the growing material, a supporting plate for supporting the heater, a bolt having one end connected to the supporting plate, a cell flange coupled to a lower flange of an adaptor for supporting the cell assembly, bellows fixed between the supporting plate and the cell flange including the bolt, and a control nut for expanding and contracting the bellows so as to separate only the cell assembly from a vacuum chamber with entire vacuum maintained in the vacuum chamber and local vacuum released in the cell assembly. The epitaxial apparatus further includes a control valve located between an entrance flange of the vacuum chamber and an upper adaptor flange of the adaptor for introducing and maintaining vacuum in the vacuum chamber.