In an effort to clarify the physics origin of the energy confinement time scaling law in H-mode plasmas, a new analysis method is first proposed where the stored energy is separated into two parts—one coming from the marginal stability with the pedestal boundary condition and the other related to the turbulent dynamics. The method is then applied for the analysis of the global scaling law, as initial examples, focusing on the four parameters of plasma current, input power, magnetic field and density in the KSTAR-type tokamak model. It is shown that the method can provide more quantitative and explicit information on how various physics elements, such as the linear stability, nonlinear turbulent dynamics and pedestal boundary, contribute to the global scaling factor. While this method is not directly applicable, the L-mode is also considered for comparison, trying to clarify how a difference in the scaling law can occur between the H- and L-modes.