PURPOSE: To reduce absorption of a water content of an adhesive into form paper, eliminate an unevenness on a form surface, and prevent an occurrence of defective printing by a method wherein the adhesive is applied in a spot pattern to a part that is positioned on the rear surface of an area made of a sealed letter intermediate paper piece and a sealed letter lower paper piece on the top surface.

CONSTITUTION: A form for a threefold sealed letter is divided into a sealed letter upper paper piece A, a sealed letter intermediate paper piece B, and a sealed letter lower paper piece C by fold lines 5. Opening perforation lines 6 are provided on the peripheral part of the paper pieces. Sprocket holes are provided on each end through a cutting line 7. On the top surface of the form, adhesives 1, 2 in a stepped form and adhesives 3, 4 in a straight line form are provided on the peripheral edges of the intermediate paper piece B and the lower paper piece C. On the rear surface of the form, adhesives 11', 12 in a stepped form and adhesives 13, 14 in a straight line form are provided on the peripheral edges of the intermediate paper piece B and the upper paper piece A. In this case, the adhesive 11' is provided in a broken line (spot) form to prevent an occurrence of a projected unevenness on the top surface of the form.