Reduced activation ferritic/martensitic (RAFM) steels have been applied to structural materials for Test Blanket module of nuclear fusion reactors because of the low activation capability, good high temperature mechanical properties and long period experience for nuclear applications. In the conventional RAFM steel (Eurofer97), MX precipitates improve microstructural stability and impede dislocation glide within lath, contributing to high-temperature mechanical properties. In this study, Ti was added to the conventional RAFM steel (Ta/Ti RAFM) in order to increase the fraction of MX precipitates. The weldment of RAFM steel was investigated since the welding is inevitable to manufacture blanket. Gas tungsten arc welding (GTAW) and electron beam welding (EBW) processes were conducted to identify variation of microstructures and mechanical properties upon welding heat input. Microstructures of Eurofer97 and Ta/Ti RAFM steels consisted of martensite. As the result of the tensile tests at 550 oC, the weldment of Ta/Ti RAFM steel exhibited superior properties to Eurofer97 steel regardless of the welding process. From transmission electron microscopy analysis, it resulted from high fraction of MX and small size of M23C6 which contribute to microstructural stability. However, the weldment of Ta/Ti RAFM steel showed inferior creep properties compared to Eurofer97 steel. It is considered that the cause of this is that grain boundary sliding occurred easily during creep deformation due to grain refinement by the addition of Ti, and degradation rapidly proceeded due to the high initial dislocation density. Therefore, it is necessary to control the Ti content and heat treatment conditions in order to improve the creep life of Ta/Ti RAFM steel. From the comparison of mechanical properties upon the welding process, GTAW-applied sample exhibited inferior tensile and creep properties compared to EBW-applied sample. It is closely related to the fracture location. The fracture of GTAW-applied sample occurred in Over-Tempered HAZ (OTHAZ) which is the weakest region of weldment. In contrast, the fracture of EBW sample occurred in base metal, which was associated with narrow HAZ width according to low heat input. Therefore, the application of EBW process with low heat input is favorable to secure stability of blanket structure. From electron back scattered diffraction and electron probe micro-analysis, it was confirmed that creep fracture of GTAW-applied sample occurred at Inter-Critical HAZ (ICHAZ) included in OTHAZ. The creep fracture was attributed to the stress concentration in ICHAZ, which is the softest region of weldment, and M23C6 precipitates at grain boundary.