To provide a manufacturing method of a coupling substrate capable of minimizing deformation or displacement of an element substrate when forming a split groove.

The manufacturing method of a coupling substrate includes the steps of: forming a split groove 5 that splits a plurality of element substrates 3, in the second principal surface 1a on the side opposite from a first principal surface 1b, after bonding an adhesive sheet 7a having adhesive force of 0.09 N/20 mm or higher to the first principal surface 1b of an unbaked coupling substrate 1 becoming the element substrates 3; and burning the unbaked coupling substrate 1 after peeling the adhesive sheet 7a from the first principal surface 1b.