PURPOSE: To provide a production method of filter cloth in which a nonwoven fabric sheet comprising ultra-fine fibers and a needle felt are joined into one body by needle punching and the needle holes produced on the nonwoven fabric sheet surface by punching are sealed to improve the surface smoothness while the surface trapping property for fine particles is not lost.

CONSTITUTION: A nonwoven fabric sheet 3 comprising ultra-fine fibers and a needle felt 2 are laminated and joined into one body by needle punching. The needle holes 7 remaining on the surface of the nonwoven fabric sheet 3 by needle punching are reduced in size by heating, or the needle holes 7 are closed by melting the structural fibers 6 of the needle felt 2 projecting through the needle holes 7 to the surface of the nonwoven fabric sheet 3.