The Structure of a plane shock wave which propagates in a plasma without magnetic fields is investigated by using the fully ionized model of the ion and the electron gases. The transport equations are of the Navier-Stokes type, the viscosity of the ion and the thermal conductivity of the electron being taken into account. To calculate the collision terms in the shocked region, the Mott-Smith type and the local equilibrium type are assumed to the distribution functions of the ion and the electron respectively, and the Fokker-Planck equation is employed. This formulation can always give the continuous solutions which do not miss a physical meaning for all Mach numbers. Then the three-fluid model which improves the transport equations for the ion is proposed. Alternative forms of considering the momentum of the electron are shown, too. In adition, the several authors' contributions to the structurs of plane shock waves, caused by the collisions of the composed particles or by the external magnetic field without collisions, are reported concisely.