In a sealed letter producing device which folds and seals, with a content, an envelope sheet on which pressure-sensitive adhesives are provided, sealing with pressure rollers smaller than in conventional rollers is achieved.
Pressure-sensitive adhesives 106 are provided in both edge portions in the width direction of an envelope sheet 100, and remoistening paste 107 is provided inwardly of both edge portions. The remoistening paste is moistened when the envelope sheet wrapping a content is bent and formed into an envelope 50, the entire surface of the envelope is pressurized by low-pressure rollers and adhered with the remoistening paste, and further only both edge portions of the envelope 50 are pressurized by an upper and lower set and a left and right pair of the pressure rollers 80, 80 having a small width to adhere the pressure-sensitive adhesive 106. High pressure required for adhesion of the pressure-sensitive adhesives is only necessary in both edge portions of the envelope, and therefore small pressure rollers 80 will suffice.