The invention provides a permselective material comprising a polymer having an organosiloxane skeleton and containing a dispersed solid additive, wherein when oxygen and nitrogen are passed through a membrane comprising the permselective material, the relation between the permeability coefficients [cm 3 cm sec -1 cm -2 cmHg -1 ] of oxygen and nitrogen at a temperature of 23+2 DEG C under a pressure difference of 1.05 atm to 1.20 atm through the membrane is expressed by Formula (1). P(O2) denotes the permeability coefficient of oxygen, while P(N2) denotes the permeability coefficient of nitrogen.