Abstract
Jupiter, Saturn and most of more than 200 extrasolar planets in the past decade are gas giant planets. Their interior structures are still poorly known. This is because the current uncertainties in their interiors are due to the three following factors; heat transfer, observational precisions and equations of state for materials, especially hydrogen and helium, under high pressure and temperature.
We considered the three factors as the differences in mechanisms of heat transfer, errors in observational properties and models for equation of state and then investigated their effects on interior structures of Jupiter and Saturn systematically.