To provide an adhesive, with which joins an ethylene-vinyl acetate copolymer and a silicone resin, required when a mouth guard is produced by joining a surface layer material made from the silicone resin to inner and outer surfaces of a mouth guard substrate made from the ethylene-vinyl acetate copolymer.

This adhesive for the ethylene-vinyl acetate copolymer and the silicone resin includes: 100 pts.wt. of an organic solvent (a); and 0.1-20 pts.wt. of a siloxane-modified unsaturated ester polymer (b), preferably a siloxane-modified unsaturated ester polymer having a reactive functional group for a hydrosilylation reaction.