A first silicon carbide substrate having a first back-side surface and a second silicon carbide substrate having a second back-side surface are prepared. The first and second silicon carbide substrates are placed so as to expose each of the first and second back-side surfaces in one direction. A connecting portion is formed to connect the first and second back-side surfaces to each other. The step of forming the connecting portion includes a step of forming a growth layer made of silicon carbide on each of the first and second back-side surfaces, using a sublimation method of supplying a sublimate thereto in the one direction.