To perform the vacuum lock of a vacuum insulation body at a low cost and in a state of high durability and reliability to a leak, and to quickly perform evacuation in the preceding stage of the vacuum lock.

The vacuum heat insulation body is constituted by sealing an evacuation port 24 after evacuating air from an inner space 22 with double walls. The surroundings of the discharge port 24 are covered by a pot 26 communicating with an evacuation means 30. At least a part 31 of the wall part of the pot 26 is formed of a transparent material. After evacuating air form the inner space 22 with the double walls by the evacuation means 30, the evacuation port 24 is covered with a sealing member 34 in the pot 26, a light beam 35 is introduced into the pot 26 after making the light beam 35 pass through the part 31 with the transparent wall part from the outside of the pot 26, and the light 35 is radiated onto a part where the evacuation port 24 is covered with the sealing member 34 so as to seal the discharge port 24 by welding.