The present paper discusses the heat loss analysis in modeling of the solid oxide fuel cell (SOFC). Conventionally, adiabatic assumption is a reasonable assumption for building the numerical model of the SOFC. However, the heat loss is one of important issues to optimize the system design for the SOFC development, considering the characteristic which strongly depends on its operating temperature. The static and dynamic modeling has been conducted with model extension to analyze the heat loss in the SOFC. The result confirms the reasonability of the adiabatic assumption, however the transient capability is strongly affected due to the large heat capacity.