PURPOSE: To form multiple high quality epitaxial layers on a crystal substrate by a method wherein the partitions between respective deposition elements in a main chamber are composed of multiple layers making gaps while the end parts of the partitions are formed so that the controlled gas after passing through the respective gaps of the partitions may be diffused making specified angles.

CONSTITUTION: When gas of specified pressure is respectively fed to nozzles 11b, 11b', running in parts 11a, 11a', partitions 13a and 13b, 13b and 13c, 13c and 13d, the gas running in the gaps between respective partitions is jetted into the dotted diffusing region as shown by A conforming to the opening angles made in the opening parts formed at respective end parts and then exhausted from an exhaust port 12a. In such a state, the chamber main body 11 is heated at e.g., 600-700°C while the material component evaporated from melted material sources 7 as well as the material gas fed from the running-in port 11a are fed to a crystal substrate 5 to deposit specified epitaxial layers (InGaAs layer) on the crystal substrate 5.