PURPOSE: To provide a manufacturing method of a bonded SOI substrate whereby it can be formed, without reducing the diameter of a wafer, the peripheral ground part can be easily formed into a mirror surface and the warp of the finished adhered SOI substrate can be possibly suppressed.

CONSTITUTION: Either or each of a first semiconductor wafer 1 to form a device surface and a second semiconductor wafer 2 to form a support has a dielectric layer 5. The manufacturing method of a SOI substrate comprises steps closely contacting the mirror faces of both wafers and are heat treating them in an oxidizing atmosphere to adhere them, grinding the marginal edge of the wafer 1 as deep as not damaging the wafer 2, and exposing an oxide film 6 formed on the marginal edge of the wafer 2 in the oxidizing atmosphere. The etching liq. for etching uses a water mixture of ethylene diamine and pyrocatechol or water soln. of tetramethyl ammonium hydroxide.