In recent years, accompanying the miniaturization of semiconductor process, a tendency to thin the thickness of the insulating layer formed between the respective wiring layers, and so that the parasitic capacitance from being generated at between each wiring layer, as a material of the insulating layer of the multilayer wiring, the dielectric constant is low the material has been applied. However, Low-k material is configured, the low strength material itself, compared with the conventional insulating layer. Further, in the Low-k material of the porous type, more fondly structurally. The present invention, in the method for manufacturing a semiconductor device having a multilayer wiring layer which includes a Low-k layer, after forming the groove with a blade having a taper with respect to the semiconductor wafer, the groove width than the step-cut method for dividing a thin straight blade the when the dicing process, the multilayer wiring part, and the cutting in the covered state by the tapered surface, and after that, that part has as this does not contact me wafer are separated by a thin blade, the damage to the relatively fragile Low-k layer for there is no giving.