To provide an adhesive between an alginate impression material and an impression tray, exhibiting high bonding strength to any tray made of a metal, a resin or a modeling compound and having high operability.

The adhesive between a dental alginate impression material and an impression tray comprises a coupling agent containing an amino group in its molecule, preferably 3-aminopropyltrimethoxysilane, 2-aminoethylaminomethyltrimethoxysilane, 3-(2-aminoethylaminopropyl)trimethoxysilane, 3-aminopropyltriethoxysilane or the like, having a molecular weight of 150-300 and a solvent, preferably at least one solvent selected from the group consisting of an alcohol, acetone and an acetic ester.