An apparatus for producing a microporous plastic film comprising a pair of vertical columns; a pair of stationary frames each fixed to each vertical column such that they are positioned inside the vertical columns; a pair of movable frames rotatable under the stationary frames; a pattern roll rotatably supported by the stationary frames at a fixed position; an anvil roll movable up and down along first vertical guide rails of the stationary frames; and a lower backup roll movable up and down along second vertical guide rails of the movable frames; the pattern roll being in parallel with the anvil roll; the first and second vertical guide rails being distant from the vertical columns on one side, such that rotating movable frames and lower backup roll do not come into contact with the vertical columns; with the lower backup roll inclined to the anvil roll in a horizontal plane, large numbers of fine pores being formed on the plastic film by the high-hardness, fine particles of the pattern roll.