PURPOSE: To obtain a heat cutter device of an automatic sealing machine capable of enhancing a film feeding reliability and improving finish of sealing.

CONSTITUTION: A heat cutter 19 is composed of a cutting blade 19a having a heater, a base 19b, and an abutting/separating means for reciprocating both the cutting blade and the base to a cutting position. A film presser member is provided downstream of the cutting blade of the heat cutter for preventing the rear end of a fused cut film from adhering to the cutting blade and moving in the same direction with the cutting blade when the cutting blade is retracted from the cutting position. Furthermore, an anti-fuming shutter supported rotatably about a journal and pressed toward the cutting blade is provided upstream of the cutting blade of the heat cutter for shielding the cutting blade from a document feed path when the cutting blade is on a non-cutting position.