A method of fabricating a reaction container according to the disclosure comprises putting graphite power in a molded member; and pressing the molded member, wherein the graphite powder comprises first graphite powder and second graphite powder having different particle sizes. A vacuum heat treatment apparatus comprises a chamber, a reaction container in the chamber, and a heat member heating the reaction container in the chamber, in which the reaction container comprises graphite, and the reaction container has a concentration in the range of 1.8 to 2.0.