An analysis of dynamic behavior is carried out in the case when dynamic load with central symmetry is applied on the inner surface of the cavity with central symmetry of a thick-walled elastic-work hardening plastic sphere. The static stress-strain curve for the material in simple tension is assumed to be a smooth curve, concave toward the strain axis. Formulas are derived of the propagation speeds of spherical waves in an isotropic elastic-work hardening plastic body. Ordinary differential equations are derived among physical quantities along characteristic curves. Formulas of propagation speeds of the spherical waves in approximate bodies such as the elastic-linear hardening plastic, the elastic-perfectly plastic, the rigid-work hardening plastic, the rigid-linear hardening and the rigid-perfect plastic bodies are derived from those in the elastic-work hardening plastic body. Calculated results are also presented on the basis of the propagation theory of the spherical waves in the elastic-work hardening plastic body.