The invention provides a break method capable of efficiently surely breaking a composite substrate in such a state that there is no remaining unbroken portion, and to provide a break device therefor. There is provided a break method for a composite substrate W in which a resin layer 3 is formed on one side of a substrate body 1 comprising brittle materials via an adhesive layer 2 and plural rows of scribe line S are formed on the surface of the substrate body 1. The method comprises: a first break process of placing the substrate body 1 at a lower side and pressing the blade tip of a break bar 8 into a resin layer 3 and the adhesive layer 2 while cutting into by sticking the composite substrate W to an adhesive tape 5 and by pressing the break bar 8 to the scribe line S from the upper face of the resin layer 3 and bowing down the substrate body 1 below to break the substrate body 1 along the scribe line S; and a second break process of bowing down again the broken line L broken in the first break process to break a remaining unbroken portion by placing the adhesive tape 5 on an upper side and press-rolling a roller 13 on overall width of the upper face of the composite substrate W.