Thin multilayered films of [Pt(1.2 nm)/Mn(1.2 nm)/Sb(2.6 nm)] and [Pt(1.0 nm)/Mn(2.0 nm)/Sb(2.0 nm)] were prepared on glass substrates by an ion-beam sputtering method, and the formation of the C1_b–PtMnSb phase in the as-deposited films was investigated by means of X-ray diffraction and transmission electron microscopy. The multilayered samples produced at room temperature consisted of a layered structure of amorphous or nano-crystalline phases. In contrast to this, as the substrate temperature increased up to about 473 K, inter-layer mixing among the constituent multilayers was found to occur and the PtMnSb phase was evolved preferentially. In addition, the platinum layer inserted as a buffer between the glass substrate and films showed a significant effect on the growth of the PtMnSb phase with preferred orientation.