To provide an adhesive composition that is sufficiently good in any of low-temperature adhesiveness, fluidity when heated, and reliability after heat curing, and a film-shaped adhesive, an adhesive sheet, and a semiconductor device using the same.

The adhesive composition contains (A) a polycondensation polymer having a Tg of 150°C or lower and (B) a thermosetting resin, wherein (A) the polycondensation polymer is obtained by performing polycondensation of an acid including a dimer acid which is a dimer of a 20-50C unsaturated fatty acid and a diamine and/or a diisocyanate.