The turbulent-nonturbulent interface in the boundary layers has been investigated experimentally. Five-component decomposition of the fluctuating velocities are introduced and equations for momentum and kinematic energy of turbulent and nonturbulent fluids are derived to discuss energy convert mechanisms. The experiment was made in an equilibrium turbulent boundary layer subjected to accelerating free stream velocity. The correction to the logarithmic velocity profile considering non-parallel streamline works well under the favorable pressure gradient. The wake component in the outer layer disappears without entrainment. The diffusion in the turbulent kinematic energy equation is strongly suppressed in the outer layer. The interaction between turbulent and nonturbulent fluids can be examined with the aid of convert terms involved the equation derived from five-component decomposition. Motions contributing energy convert can be detected by investigating the production terms.