[en] The substitution of magnetic Fe²⁺ for nonmagnetic Cu⁺ in the Cu_1-xFe_xIr₂S₄ system causes drastic changes in electromagnetic behavior. For x = 0.01 and 0.025, the Peierls-like phase transition step ΔM in magnetization increases with x increasing, and an unexpected spin transition occurs at T^*∼120 K. This may be attributed to the spin-polarization of the Ir⁴⁺ ions by the Fe²⁺ ions. When x exceed 0.1, the Peierls-like phase transition is suppressed completely. The magnetic state for Fe doped samples transforms from ferromagnetic (FM) to paramagnetic (PM), and back to the FM state again with the increase of x. For the highly doped samples, the FM domains formed by Fe²⁺ ions result in another transition at T^**∼110 K and the cluster-spin glass transition.