To provide a machine for producing extra-fine fiber felt, designed to quantitatively feed a felt forming unit section with extra-fine fibers, and to provide a method for producing the felt.

The machine for producing the extra-fine fiber felt has the following construction and mechanism: A net conveyor 10 equipped with a conveying net 9 is set up in between the felt forming unit section 5 and a unit section 2 for crudely opening mat-form extra-fine fibers. The conveying net 9 is sucked from below and crudely opened fibers are accumulated on the net 9. At a specified position midway of a conveying path through which the resultant extra-fine fiber assembly 12 is conveyed, there is provided a differential pressure gauge 13 functioning to detect the difference between the pressure above the extra-fiber assembly 12 and that below the same as it passes through the specified position. Based on the result given from the differential pressure gauge 13, the feed velocity of a crudely opening conveyor 6 is controlled so that the differential pressure come to a set value.