PROBLEM TO BE SOLVED: To provide a mouthpiece which is easy to manufacture and excellent in a feeling of wear and durability.SOLUTION: A mouthpiece worn on the tooth row has a layer structure including a layer (A) positioned on the tooth row side when worn on the tooth row of the mouthpiece and a layer (B) which is layered on the layer (A) and positioned opposite to the tooth row seen from the layer (A) when worn. The layer (A) contains at least one kind of elastomer selected from a group composed of acrylic thermoplastic elastomer and polyester-based thermoplastic elastomer. The layer (B) contains at least one kind of high polymer selected from a group composed of poly(meth)acrylate and polyester. Adhesive strength between the layer (A) and the layer (B) is 30 MPa or more, flexural modulus of the layer (A) ranges from 50 MPa to 300 MPa, flexural modulus of the layer (B) is higher than flexural modulus of the layer (A), and difference between the flexural modulus of the layer (A) and the flexural modulus of the layer (B) ranges from 1000 MPa to 3000 MPa.SELECTED DRAWING: Figure 12COPYRIGHT: (C)2020,JPO&INPIT
