Behaviors of solute elements segregation and primary carbides in the solidification structure of rare earth metals(REM) treated 0.35C-0.45Si-0.33Mn-4.9Cr-1.2Mo-0.8V ingots have been investigated. The important results are summarized as follows. 1) REM addition brought about a remarkable reduction of center-segregation, center-blow hole, and enlargement of equiaxed zone and fine solidification structure. 2) REM addition brought about a remarkable reduction of solute elements segregation area in ingots, so that it resulted in refinement of primary carbides. 3) Crystallized carbides in solute elements segregation area of 5Cr and REM treated ingots were MC of dendrite type and M₂C of skeleton type. Dendrite crystal, solute elements segregation area, and M₂C changed into γ-Fe, MC, M_7C₃, M_(23)C_6 and M_6C by 845℃ soaking treatment. REM addition did not influence on the carbide composition at the same heat treatment.