The present invention discloses an adhesive for orthodontic attachments, which contains (A) a polymerizable monomer, (B) a polymerization initiator and (C) a fluorescent dye and, when cured, exhibits a fluorescence spectrum having a peak at 400 to 800 nm. As the polymerization initiator (B), there is preferably used a compound which generates a radical through the transfer of hydrogen between two components, or a compound which generates a radical species through intramolecular cleavage. As the fluorescent dye (C), a coumarin type dye is used preferably.