A vacuum packaging apparatus, comprising: a chamber that accommodates a packaging bag in which a packaged object including a liquid is received; a degasifier that degasses inside the packaging bag by decompressing inside the chamber; a filling-opening closing device that is provided inside the chamber, the filling-opening closing device for opening and closing a packaged-object filling opening (Ba) of the packaging bag; a sealing device that seals the packaged-object filling opening (Ba) that is in a closed state; an inflation detection means that is capable of detecting a change of position of at least a part of the packaging bag to a predetermined position, which is a position the part of the packaging bag reaches when the liquid in the packaging bag boils and the packaging bag is inflated inside the chamber; and a controller that controls the degasifier, the filling-opening closing device, and the sealing device, wherein: the controller controls the filling-opening closing device to close the packaged-object filling opening (Ba) of the packaging bag, controls the degasifier to perform decompression inside the chamber to a level at which the liquid boils, controls the filling-opening closing device to open the packaged-object filling opening (Ba) and controls the degasifier to stop degassing when the inflation detection means detects a change of position of at least a part of the packaging bag to the predetermined position, and controls the sealing device to seal the packaged-object filling opening (Ba). a chamber that accommodates a packaging bag in which a packaged object including a liquid is received; a degasifier that degasses inside the packaging bag by decompressing inside the chamber; a filling-opening closing device that is provided inside the chamber, the filling-opening closing device for opening and closing a packaged-object filling opening (Ba) of the packaging bag; a sealing device that seals the packaged-object filling opening (Ba) that is in a closed state; an inflation detection means that is capable of detecting a change of position of at least a part of the packaging bag to a predetermined position, which is a position the part of the packaging bag reaches when the liquid in the packaging bag boils and the packaging bag is inflated inside the chamber; and a controller that controls the degasifier, the filling-opening closing device, and the sealing device, wherein: the controller controls the filling-opening closing device to close the packaged-object filling opening (Ba) of the packaging bag, controls the degasifier to perform decompression inside the chamber to a level at which the liquid boils, controls the filling-opening closing device to open the packaged-object filling opening (Ba) and controls the degasifier to stop degassing when the inflation detection means detects a change of position of at least a part of the packaging bag to the predetermined position, and controls the sealing device to seal the packaged-object filling opening (Ba). controls the filling-opening closing device to close the packaged-object filling opening (Ba) of the packaging bag, controls the degasifier to perform decompression inside the chamber to a level at which the liquid boils, controls the filling-opening closing device to open the packaged-object filling opening (Ba) and controls the degasifier to stop degassing when the inflation detection means detects a change of position of at least a part of the packaging bag to the predetermined position, and controls the sealing device to seal the packaged-object filling opening (Ba).