Abstract: A mouthguard includes a mouthguard body and a film structure. The mouthguard body includes a front part, a rear part and a bottom part. A trench is defined by the front part, the rear part and the bottom part collaboratively. The film structure includes a first surface and a second surface. A marked pattern is printed on the second surface. The second surface of the film structure is attached on an outer surface of the front part of the mouthguard body while the mouthguard body is produced by an injection molding process, so that ink or pigment of the marked pattern is confined between the mouthguard body and the film structure without being exposed to outside.