To improve the yield in a peeling process and improve the yield in a manufacturing process of a flexible light-emitting device or the like, a peeling method includes a first step of forming a peeling layer over a first substrate, a second step of forming a layer to be peeled including a first layer in contact with the peeling layer over the peeling layer, a third step of curing a bonding layer in an overlapping manner with the peeling layer and the layer to be peeled, a fourth step of removing part of the first layer overlapping with the peeled layer and the bonding layer to form a peeling starting point, and a fifth step of separating the peeling layer and the layer to be peeled. The peeling starting point is preferably formed by laser light irradiation.