Exciton luminescence and intracenter luminescence (IL) of Mn²⁺ ions in Cd_0.6Mn_0.4Te/Cd_0.5Mg_0.5Te structures with quantum wells (QWs) 7, 13, and 26 monolayers thick were studied. It was established that in QWs the intensity of exciton luminescence with respect to that of IL is a few orders of magnitude higher than that in bulk crystals. The spectral position of manganese IL profile changes noticeably in going from a bulk crystal to a QW of the same composition. The nonexponential parts of the IL decay curves are determined by excitation migration and the cooperative upconversion process, whose contribution is high under strong excitation and efficient migration. At 77 K, the IL decay constant τ within the exponential region increases with decreasing QW thickness. The decay constant τ in a QW, unlike in a bulk Cd_0.5Mn_0.5Te crystal, decreases substantially under cooling from 77 to 4 K.