A thermosensitive adhesive contains a side chain crystal polymer having a melting point of 20-30° C., and a tackifier. The side chain crystal polymer is obtainable by adding a metal chelate compound in the following amount of addition (A) into the following copolymer, followed by a crosslinking reaction. Adhesive strength is to be deteriorated at a temperature below the melting point. The copolymer is obtainable by polymerizing 25-30 parts by weight of (meth)acrylate having a straight-chain alkyl group having 16 to 22 carbon atoms, 60-65 parts by weight of (meth)acrylate having an alkyl group having 1 to 6 carbon atoms, 1-10 parts by weight of a polar monomer, and 1-10 parts by weight of a reactive fluorine compound. The amount of addition (A) is 3-10 parts by weight with respect to 100 parts by weight of a copolymer.