We propose a method for achieving stable topology optimization for structures made of elastoplastic materials using a reasonable elastoplastic material model within the framework of finite strain nonlocal theory. Specifically, the model, called the subloading surface model, is newly incorporated into the primal problem, which realizes a gradual change of the deformation process from pure elastic to material-specific plastic hardening. Accordingly, unlike conventional plastic models, the stress-strain curve yields a smooth function, and the material Jacobian used in the adjoint method results in a continuous function. A numerical example is presented to show how the subloading surface model can solve the oscillatory behavior of deformation states in the optimization process caused by conventional plastic models.