To provide a rectangular envelope having a sealing paste part at a seal part wherein an indication part of a destination and/or a sender can be printed by a laser beam printer.

The rectangular envelope 10 comprising a surface and a rear which are opposite to each other, having a seal 12 extending from a side of the surface and a bottom formed of the surface and the rear and opposite to the side of the seal part 12 and formed with a sealing paste part 34 and a peeling tape 35 for covering the paste part 34 on a rear of the seal part 12 includes a protection piece 22 formed on a rear to be opposite to the rear of the seal part 12. Therefore, even if the rectangular envelope is put in a laser beam printer and a destination is printed on a surface blank in a predetermined layout, since the tape 35 is protected by the opposite protection piece 22, the tape 35 may not be peeled off due to heat of the printer, and the paste part 34 may not attach to a drum or a roller of the printer. Thus the destination can be continuously and smoothly printed.