We studied the dependence of the magnetic properties on the Mn concentration of IV-VI diluted magnetic semiconductor Si1βxβMnxβTe1.5β single crystals prepared by using the vertical Bridgman technique. X-ray studies showed that the crystal structure was hexagonal. The magnetization measurement of Si1βxβMnxβTe1.5β showed a ferromagnetic ordering up to 80 K. With increasing Mn concentration, the saturation magnetization increased and the coercive field increased, as shown in the hysteresis loop. For x = 0.20 and 0.31, a slope change in the resistivity was observed around 80 K and corresponded to a ferromagnetic (FM)-paramagnetic (PM) phase transition.ope