Solid oxide fuel cells (SOFCs) have the highest energy conversion efficiency among various power generators and expected to be earlier commercialization. Our study aims to develop fabrication techniques of microtubular SOFC bundles and establish realistic bundle structure for kilowatt class module. So far, we have succeeded to establish fabrication technology of the microtubular SOFC bundles using porous supporting matrices. In this study, the simulation study of the microtubular SOFC bundle was carried out to understand Joule heat and temperature distribution in the microtubular SOFC bundle during operation. The results indicated that the method of current collection had to be carefully considered, since the total output power loss of the bundle was estimated to be 27.8%. The temperature distribution of the bundle using porous MgO matrices turned out to be moderate compared with that in the previous bundle using porous $(La,Sr)(Co,Fe)O3$ matrices due to the difference in the thermal conductivity of each matrix constitute.