Abstract: A vacuum forming method of manufacturing a product by using a vacuum forming mold including a vacuum forming product protrusion forming device is provided, the vacuum forming product protrusion forming device including: a body portion fixed on a side of the vacuum forming mold; a guide portion inserted in the body portion to be movable in an up and down direction with respect to the body portion; a hinge portion connected to a side of the guide portion; and a protrusion forming portion connected to the side of the guide portion through the hinge portion to be pivotable within an angular range around the hinge portion, the vacuum forming method including: placing material on the vacuum forming mold; forming the material by vacuum pressing; separating a formed product from the vacuum forming mold.