A core bar for an elastic crawler, the core bar including: a core bar base that extends in a width direction of an endless belt-like elastic body and is embedded in the elastic body; a pair of projection portions (32L,32R) that project to an inner circumferential surface side of the elastic body at a center portion in a longitudinal direction of the core bar base; and a pair of rail portions (36L,36R) that project from the core bar base to the inner circumferential surface side of the elastic body on opposite outer sides of the pair of projection portions (32L,32R) and each include a track roller support surface supporting a track roller rolling on the inner circumferential surface of the elastic body, wherein the core bar comprises a pair of rail extension portions (36L,36R) that project from the core bar base to the inner circumferential surface side of the elastic body and each include a top surface formed in such a manner as to continue from the track roller support surface, the top surface extending from the rail portion (36L,36R) toward the center side in the longitudinal direction of the core bar base, characterized in that the projection portions (32L,32R) comprise a head portion and a base portion having a dimension in a width direction of the core bar smaller than that of the head portion; in each rail extension portion (36L,36R), the top surface of rail extension portion (36L,36R) is formed on both sides in the width direction of the core bar with the base portion therebetween; the top surfaces formed on both sides in the width direction of the core bar respectively extend from the rail portion (34L,34R) to a distal end of the projection portion (32L,32R); and in each rail extension portion (36L,36R), the dimension, in a width direction of the core bar, of the rail extension portion (36L,36R) including the base portion and the top surfaces on both sides thereof is decreases from the rail portion (34L,34R) toward the distal end of the projection portion (32L, 32R). a core bar base that extends in a width direction of an endless belt-like elastic body and is embedded in the elastic body; a pair of projection portions (32L,32R) that project to an inner circumferential surface side of the elastic body at a center portion in a longitudinal direction of the core bar base; and a pair of rail portions (36L,36R) that project from the core bar base to the inner circumferential surface side of the elastic body on opposite outer sides of the pair of projection portions (32L,32R) and each include a track roller support surface supporting a track roller rolling on the inner circumferential surface of the elastic body, wherein the core bar comprises a pair of rail extension portions (36L,36R) that project from the core bar base to the inner circumferential surface side of the elastic body and each include a top surface formed in such a manner as to continue from the track roller support surface, the top surface extending from the rail portion (36L,36R) toward the center side in the longitudinal direction of the core bar base, characterized in that the projection portions (32L,32R) comprise a head portion and a base portion having a dimension in a width direction of the core bar smaller than that of the head portion; in each rail extension portion (36L,36R), the top surface of rail extension portion (36L,36R) is formed on both sides in the width direction of the core bar with the base portion therebetween; the top surfaces formed on both sides in the width direction of the core bar respectively extend from the rail portion (34L,34R) to a distal end of the projection portion (32L,32R); and in each rail extension portion (36L,36R), the dimension, in a width direction of the core bar, of the rail extension portion (36L,36R) including the base portion and the top surfaces on both sides thereof is decreases from the rail portion (34L,34R) toward the distal end of the projection portion (32L, 32R).