PURPOSE: To obtain an SOI substrate, cost of which is reduced and which has a large diameter, by bonding an silicon layer onto an insulating substrate.

CONSTITUTION: A substrate in which an silicon layer 4 is bonded onto an insulating substrate 1 is used as an SOI substrate. An silicon thin-film 2 is formed onto the insulating substrate 1, an aluminum thinfilm 3 is shaped, the substrate 1 and the silicon layer 4 are fast stuck, and the SOI substrate is manufactured through desired heat treatment. The silicon thin-film 2 is formed onto the whole surface of the insulating substrate 1 by employing a CVD method, etc., and the aluminum thin-film 3 is shaped onto the whole surface through a sputtering method, etc. The insulating substrate and the silicon layer 4 are joined, and the insulating substrate and the silicon layer 4 are bonded completely through heat treatment at approximately 500°C. The aluminum thin-film generates a eutectic reaction and is diffused into the silicon film 2 at that time. Accordingly, the SOI substrate having a large diameter using the silicon layer, cost of which is reduced and which has high quality, can easily be manufactured.