To provide a simple manufacturing method of a semiconductor substrate including a single-crystal semiconductor film with less defects on an insulation surface, and provide a manufacturing method of a semiconductor device with high yield.

A manufacturing method of a semiconductor substrate comprises: forming an insulation layer on a surface of a single-crystal semiconductor substrate; forming an embrittled region by irradiating the single-crystal semiconductor substrate with ions via the insulation layer while etching the insulation layer; forming a junction layer on the surface of the single-crystal semiconductor substrate; attaching the single-crystal semiconductor substrate to a supporting substrate via the junction layer; forming a cleavage plane in the embrittled region by heat treatment; and separating a part of the single-crystal semiconductor substrate.