A method for plasma-treating a porous body, comprising the steps of generating plasma using an inert gas or a mixed gas of an inert gas and a reactive gas, (a) blowing the resultant plasma gas to the porous body at a flow rate per a unit area of the porous body of 0.002 to 2 L/minute/cm2, (b) sucking the porous body in a plasma gas atmosphere, or (c) sucking the porous body while blowing the plasma gas to the porous body at said flow rate, thereby treating the plasma the surfaces and pores of said porous body with plasma.