To obtain an adhesive exhibiting strong adhesive force to an adherend after bonding without deteriorating the characteristic high initial adhesive strength of the adhesive.

The objective adhesive has a surface modified with a functional group exhibiting adhesive reactivity by the interfacial contact reaction and keeps the initial tackiness of the adhesive having unmodified surface. The surface of the modified adhesive may be modified with a copolymer of an acrylic monomer and a monomer copolymerizable with the acrylic monomer and having a primary or secondary amino group or producing a primary or secondary amino group by polymerization. The surface of the adhesive may have a 1st reactive functional group modification layer formed by interfacial reaction and a 2nd reactive functional group modification layer containing an adhesion reactive functional group and formed on the 1st modification layer by interfacial contact reaction.