In the present invention, the attempt was made to increase the denseness (to lower the porosity) of a magnesia carbon brick furthermore thereby providing the magnesia carbon brick having a high durability never found in the past. The magnesia carbon brick of the present invention comprises a magnesia raw material and a graphite, wherein the magnesia carbon brick contains the graphite with the amount thereof in the range of 8% or more by mass and 25% or less by mass and the magnesia raw material with the amount thereof in the range of 75% or more by mass and 92% or less by mass, the both amounts being relative to the total amount of the magnesia raw material and the graphite; as a grain size distribution of the magnesia raw material, the magnesia raw material having particle diameter of in the range of 0.075 mm or more and 1 mm or less is blended with the amount thereof being 35% or more by mass relative to the total amount of the magnesia raw material and the graphite, and a mass ratio of the magnesia raw material having the particle diameter of in the range of 0.075 mm or more and 1 mm or less to the magnesia raw material having the particle diameter of less than 0.075 mm is 4.2 or more; and an apparent porosity thereof after firing in reducing atmosphere for 3 hours at 1400° C. is 7.8% or less.