Provided is a spine immobilization device that is able to suppress the sense of discomfort felt when worn to a low level. A spine immobilization device is an immobilization device that immobilizes a persons spine and is provided with a sheet part and a core part. The sheet part has a sheet-like shape and is configured to be stuck to the body surface. The core part is fastened to the back surface of the sheet part. The core part is configured to extend along a spine. In this state, the core part laterally supports the spine.