To retain a boot in a fixed shape and to remove the malodor from the insole of the boot by allowing the insole part of the boot to open to outside air while the shape of the boot is retained.

The boot shape retention body 1, which retains the shape of a shaft part 21 of the boot by inserting the body shape retention body into the shaft part 21, includes a cylindrical body part 30 made of a plastic sheet 10 in which gas is previously enclosed, and a through hole 42b formed in the lower part of a side wall surface of the body part 30, or a groove part 42a formed in the lower end of the side wall of the body part 30. The body part 30 has the finite-form property because of the enclosed gas.