PURPOSE: To improve liquid sucking and holding properties by carrying out wet-type paper making process by using alkali-containing silicate glass fibers with an average diameter of 0.3∼1.0μ and bonding them together without adhesive and then forming a mat-type separator.

CONSTITUTION: Alkali-containing silicate glass fibers with an average diameter of 0.3∼1.0μ are dispersed in the water whose pH value is kept in 2∼3 and are subjected to wet-type paper making process and then a water glass layer that forms a bonding layer is generated on the surface of the glass fiber. Subsequently, the glass fibers are bonded together with water glass layer by heating the water glass layer and a mat-type separator for a storage battery with a density of 0.13 to 0.16g/cm2 is formed. As a result, the density of the separator can be reduced and space ratio can be increased. Simultaneously, liquid sucking and holding properties can be increased by removing the materials other than the glass fiber and the internal resistance of the sotrage battery can be reduced.