A belt pressure reduction device comprises a combining portion being formed by folding two sides of a plane structure so that one side covers upon another side to form an adhering section so as to form a hollow receiving space within the combining portion for receiving an air cushion and a belt; one end of the air cushion being an airbag and another end thereof being an air inflation unit. The inflation unit serves to inflate air into the air cushion so as to cause the airbag to be elastic. The air cushion is not separated from the combining portion. The inflation unit of the air cushion exposes out of the combining portion. The combining portion is formed with at least one air hole. Two ends of the combining portion are foldable and unfoldable repeatedly.