A novel type of upper jaw- and lower jaw-mouthpieces are provided. The mouthpieces are two separate upper jaw- and lower jaw-mouthpieces (1, 2). The upper jaw- and lower jaw-mouthpieces (1, 2) are bonded and fixed with at least one adhesive piece (3, 31 to 36), and the adhesive piece (3, 31 to 36) allows the upper jaw- and lower jaw-mouthpieces (1, 2) to be movable within a limited range. The limited range is, for example, movement of the upper jaw- and lower jaw-mouthpieces (1, 2) upward, downward, forward, rearward, leftward, and rightward within a range of 1 to 8 mm.
