A reaction chamber includes a reactor wall, a susceptor contacting the reactor wall to define a reaction space and a gas flow control device and a showerhead member stacked between the reactor wall and the susceptor. The showerhead member includes a gas channel and a showerhead. Penetration holes are formed through a protruding lateral portion of the gas flow control device, and the reactor wall and a lateral portion of the showerhead member are spaced apart from each other to form a gas discharge path. Gas remaining in the gas discharge path is discharged through the penetration holes and a gas outlet formed in an upper portion of the reactor wall. Because of the reaction space and the gas discharge path, unnecessary regions are removed to rapidly change gases from one to another, and thus atomic layer deposition may be performed with high efficiency and productivity.