Numerical simulation models to analyze the expansion behavior of the LaCrO3 interconnector and the resulting stresses under the cell operating conditions were proposed. This model calculation was the first precise analysis including most phenomena which should be considered in terms of stress and mechanical reliability of the interconnector under practical operations. As the first step, using a single-unit model with bipolar channels, the profiles of the oxygen vacancy concentration in the interconnector under practical cell operating conditions were calculated. As the second step, using the calculated profiles of the oxygen vacancy concentration in the interconnector, the deformations of the interconnector and the resulting internal stresses were simulated. It was found from the simulation that the nonuniform expansion of the interconnector under a cell operating condition would cause large internal stresses comparable to the thermal stresses.