SiC nano-powder was synthesized by mechanical alloying method, and then consolidated by Spark plasma sintering without any sintering additives. Crystallite size of sintered SiC was increased from 26 to 61 nm with holding temperature, but relative density was practically fixed. Increasing of thermal and electrical conductivity of SiC with crystallite size was observed.1 Introduction Silicon carbide (SiC) is one of the promising candidate materials for high temperature application, because of its excellent thermal, electrical and mechanical properties. However, SiC has been known as one of the materials with low sinterability due to its thermal stability. Although nano metric SiC powder is used as starting material, the full densification is not easy without the use of sintering additives. The effect of sintering aid on thermal and electrical properties of SiC is significant, thus, it is difficult to observe the influence of structure of polycrystalline SiC on these properties.In our previous work, the consolidation of SiC nano-powder synthesized by mechanical alloying (MA) method was subsequently accomplished by Spark plasma sintering (SPS) without any sintering additives. Those sintered body has relative density of >98 % against theoretical density and grain size of about 50 nm [1]. We concluded that this phenomenon was caused by the acceleration of mass transfer occurred from the ordering process of stacking disordered structure which was formed during MA process [2][3]. However, thermal and electrical properties of that SiC have not been studied, sufficiently. In this work, the thermal and electrical properties of those dense SiC sintered body was discussed. Especially, the effect of sintering condition on those thermoelectric properties was focused.