A trench isolation junction type SOI semiconductor device which reduces substrate warpage while suppressing increase in production steps and a method for producing the same are disclosed. A junction substrate is formed by bonding a semiconductor substrate having an outer insulation film on a non-junction main surface with a semiconductor layer with an inner insulation film sandwiched therebetween. After forming a silicon nitride film as a mask for the purpose of forming a trench in the semiconductor layer, silicon nitride film accumulated on the outer insulation film is removed. By doing this, warpage of the semiconductor substrate due to discrepancies in the thermal expansion rates of the rigid silicon nitride film and semiconductor substrate can be prevented. In a junction type SOI semiconductor device formed via the method, an outer insulation film of identical thickness and identical density to an inner insulation film is formed on a non-junction main surface (i.e., rear surface) of a semiconductor substrate. By doing this, warpage of the semiconductor substrate can be prevented.