PURPOSE: To develop a thin film material aiming an oxygen enriching membrane for burning used for improving burning efficiency, or an oxygen enriching membrane for medical application used for breatching support being good in a mass productivity and having thermophilic stability by increasing concn. of oxygen in air.

CONSTITUTION: This membrane is a homogeneous membrane obtained by blending polydimethylsiloxane and polydiphenylsiloxane in a solvent containing a cross-linking agent such as benzoyl peroxide, etc., and by forming a membrane by a solution casting method or a dual membrane obtained by casting the blended solution onto a porous membrane and drying, and producing method is obtained.