  We present a gauged twistor model of a free massive spinning particle in
four-dimensional Minkowski space. This model is governed by an action, referred
to here as the gauged generalized Shirafuji (GGS) action, that consists of
twistor variables, auxiliary variables, and $U(1)$ and $SU(2)$ gauge fields on
the one-dimensional parameter space of a particle's worldline. The GGS action
remains invariant under reparametrization and the local $U(1)$ and $SU(2)$
transformations of the relevant variables, although the $SU(2)$ symmetry is
nonlinearly realized. We consider the canonical Hamiltonian formalism based on
the GGS action in the unitary gauge by following Dirac's recipe for constrained
Hamiltonian systems. It is shown that just sufficient constraints for the
twistor variables are consistently derived by virtue of the gauge symmetries of
the GGS action. In the subsequent quantization procedure, these constraints
turn into simultaneous differential equations for a twistor function. We
perform the Penrose transform of this twistor function to define a massive
spinor field of arbitrary rank, demonstrating that the spinor field satisfies
generalized Dirac-Fierz-Pauli equations with $SU(2)$ indices. We also
investigate the rank-one spinor fields in detail to clarify the physical
meanings of the $U(1)$ and $SU(2)$ symmetries.
