PURPOSE: To vacuum-pack tissue paper, etc., to obtain a volume reduction effect sufficiently by obtaining a package forming a square body of right shape free of curving, bending, etc., and by improving the convenience of a vacuum package by obtaining a necessary unsealing port at a necessary place easily and surely, when the package is unsealed.

CONSTITUTION: A vacuum-packed paper forming a square body of right shape is realized when tissue paper, etc., 1 piled up into the square body is vacuum- packed in a state where flat plates 3, 4 are put to the lap faces of the tissue paper 1, etc., and pressure 5 is applied thereto. Also, after a slit 6 of predetermined size is provided beforehand at the predetermined place of a packaging container for vacuum packaging and sealed by an adhesive tape 8, vacuum packaging is conducted and the adhesive tape 8 is peeled off so that vacuum is unsealed and an unsealing port of desired size is obtained at a desired place simply and surely.