To provide a method of manufacturing a holding seal material for a catalytic converter which hardly causes the aged deterioration in surface pressure.

A mat-like fiber assembly is formed by forming a ceramic fiber by an inorganic salt method and after firing, by three dimensionally collecting the ceramic fibers. Next, an uneven structure in which inorganic particles contained in a suspension are deposited on the outer surface of the ceramic fiber is formed by supplying the inorganic particle suspended solution into the fiver assembly and heating and firing. The fiber assembly is punched into a prescribed shape to make the holding seal material.