[en] In the frame of the Hamiltonian-Jacoby theory the tensor of angular momentum is defined through the vector-function of action. The principle of least action for a vector-function is formulated. Hamilton equations for the tensor of angular momentum are derived from the principle of least action by means of proving the opposite. The equations for the vector-function action are obtained analogous to the Hamilton-Jacoby's equation. Quantum-mechanical equations of motion for the tensor of angular momentum are derived traditionally, replacing the Hamiltonian and momentum of the system for corresponding operator. The nonrelativistic and relativistic cases are considered. It has been shown that equations describe systems with spin equal to one. In relativistic case the obtained equations generalize well-known Proca equations; in the nonrelativistic one, Pauli's equations for the spin one