Provided is an adhesive composition which is flexible, and exhibits excellent adhesion durability. The adhesive composition comprises (a) a 2-cyanoacrylic acid ester, (b) a polymer having a hydrolyzable silyl group, (c) an elastomer, and (d) an acid catalyst, in which the contents of the components (b), (c), and (d) are from 5 to 200 parts by mass, from 5 to 50 parts by mass, and from 0.0005 to 0.5 parts by mass, respectively, relative to 100 parts by mass of the component (a). Further preferably, the composition contains 0.001 to 5 parts by mass of (e) an onium salt relative to 100 parts by mass of the component (a).