A groove machining head has a dust collecting hood 40 having a suction port in the vicinity where tools 32 protrude from a bottom plate 33 of the groove machining head. When performing groove machining on a substrate W using the groove machining head 30, a blower 35 sucks air inside the dust collecting hood 40 through ducts 34. Doing so can suck dust produced by the groove machining through the suction port of the dust collecting hood 40 before attachment of the dust on the substrate W.