NOVELTY - The apparatus (1) has a gas gate (5) comprising the entrance, center and exit side rollers (11a-11c) that are positioned in a container (13) so as to form the conveyance path for elongate substrate (18), where diameter of center side roller is larger than that of other rollers. The gate clearance gap formation elements (10a-10c) are positioned with respect to the rollers. The purge gas is supplied towards the center side roller through the gap formation element (10c) such that center side roller is rotated to convey the substrate between the film formation chambers.    USE - Roll-to-roll system type semiconductor element production apparatus used for forming amorphous silicon film on elongate substrate during manufacture of solar cell, image sensor, electrophotographic photoreceptor, etc. Can also be used in plasma chemical vapor deposition (CVD) apparatus, plasma etching apparatus, etc.    ADVANTAGE - The conveyance of the substrate can be performed efficiently. The diameter of center side roller is larger than that of entrance and exit rollers so that the grip force of the substrate is larger during the conveyance process. The mixing of the impurity gas and the purge gas is prevented so that the damage to the substrate is prevented and the substrate is conveyed safely and stably without enlarging the dimension of the gas gate of the roll-to-roll system type semiconductor element production apparatus. Thus, the through-put of the roll-to-roll system type semiconductor element production apparatus is improved, and the manufacturing cost of the semiconductor element is reduced.    DESCRIPTION OF DRAWING(S) - The drawing shows the sectional view of the gas gate of roll-to-roll system type semiconductor element production apparatus.    Roll-to-roll system type semiconductor element production apparatus (1)    Gas gate (5)    Gate clearance gap formation elements (10a-10c)    Entrance side roller (11a)    Center side roller (11b)    Exit side roller (11c)    Container (13)    Elongate substrate (18)