A refractory material containing, in terms of a chemical composition as measured after being subjected to a heat treatment in a non-oxidizing atmosphere at 1000°C: 40 mass% or more of MgO; 4 to 30 mass% of a free carbon component; a total amount of 0.3 to 3 mass% of one or more oxides selected from the group consisting of B 2 O 3, P 2 O 5, SiO 2 and TiO 2; and optionally a remainder of at least one other type of additional refractory component, wherein the additional refractory component is selected from the group consisting of an Al 2 O 3 component; an oxide component selected from ZrO 2, Y 2 O 3, CaO and Cr 2 O 3; and SiC, wherein these may be added independently, or may be used in the form of a solid solution or a compound; wherein the refractory material contains a refractory microstructure constructed such that a void layer having a certain thickness is formed in an interface between a three-dimensionally continuous carbonaceous matrix and each of a plurality of MgO-containing particles residing in the carbonaceous matrix, in such a manner as to surround the MgO-containing particle, wherein an approximately continuous void layer free of solids such as carbon, is formed around each of the MgO-containing particles, wherein an average of respective MS values of ten particles selected in a microscopic observation field of the microstructure is in the range of 0.2 to 3.0%, wherein the MS value is the micro-space value indicating the ratio of a thickness of the void layer to a particle size and wherein the average of respective MS values of ten particles is determined according to the description, and wherein an inorganic compound comprised of MgO and the one or more oxides selected from the group consisting of B 2 O 3, P 2 O 5, SiO 2 and TiO 2 exists in an entirety or a part of a surface of each of the plurality of MgO-containing particles, wherein the above expression "approximately continuous" means that the void layer actually exists around the entire periphery of each of the MgO-containing particles, and even when a partial contact state between a certain one of the MgO-containing particles and an adjacent one of the MgO-containing particles or the matrix is observed during verification by microscopic observation, such a state is not a "joined or bonded" state enough to ensure fixing of the certain MgO-containing particle with respect to the adjacent MgO-containing particle or the matrix. 40 mass% or more of MgO; 4 to 30 mass% of a free carbon component; a total amount of 0.3 to 3 mass% of one or more oxides selected from the group consisting of B 2 O 3, P 2 O 5, SiO 2 and TiO 2; and optionally a remainder of at least one other type of additional refractory component, wherein the additional refractory component is selected from the group consisting of an Al 2 O 3 component; an oxide component selected from ZrO 2, Y 2 O 3, CaO and Cr 2 O 3; and SiC, wherein these may be added independently, or may be used in the form of a solid solution or a compound; wherein the refractory material contains a refractory microstructure constructed such that a void layer having a certain thickness is formed in an interface between a three-dimensionally continuous carbonaceous matrix and each of a plurality of MgO-containing particles residing in the carbonaceous matrix, in such a manner as to surround the MgO-containing particle, wherein an approximately continuous void layer free of solids such as carbon, is formed around each of the MgO-containing particles, wherein an average of respective MS values of ten particles selected in a microscopic observation field of the microstructure is in the range of 0.2 to 3.0%, wherein the MS value is the micro-space value indicating the ratio of a thickness of the void layer to a particle size and wherein the average of respective MS values of ten particles is determined according to the description, and wherein an inorganic compound comprised of MgO and the one or more oxides selected from the group consisting of B 2 O 3, P 2 O 5, SiO 2 and TiO 2 exists in an entirety or a part of a surface of each of the plurality of MgO-containing particles, wherein the above expression "approximately continuous" means that the void layer actually exists around the entire periphery of each of the MgO-containing particles, and even when a partial contact state between a certain one of the MgO-containing particles and an adjacent one of the MgO-containing particles or the matrix is observed during verification by microscopic observation, such a state is not a "joined or bonded" state enough to ensure fixing of the certain MgO-containing particle with respect to the adjacent MgO-containing particle or the matrix.