Disclosed is a boot shape keeper capable of holding a boot in a fixed shape, removing malodor from the insole of the boot by allowing the insole of the boot to be opened to outside air while the boot is held, and capable of adjusting the height to the shaft part of the boot. The boot shape keeper, which is inserted into a shaft part of a boot to keep a shape of the shaft part of a boot, includes a cylindrical body part made by forming a plastic sheet having a gas pre-encapsulated into a cylindrical shape, and at least one projecting part projecting downward from a lower end of the body part, wherein the body part has a fixed shape provided by the encapsulated gas, and the projecting part has a gas pre-encapsulated, and allows the gas to be fed into and out between the body part and the projecting part, so that the projecting part is elastically contractable up and down.