The present invention provides an adhesive composition which comprises (a) an epoxy resin, (b) a curing agent and (c) a polymer compound incompatible with said epoxy resin, and further optionally comprises (d) a filler and/or (e) a curing accelerator; a process for producing an adhesive composition, comprising: mixing (a) the epoxy resin and (b) the curing agent with (d) the fillers followed by mixing the resultant mixture with (c) the polymer compound incompatible with the epoxy resin; an adhesive film comprising the above-mentioned adhesive composition formed into a film; a substrate for mounting semiconductor comprising a wiring board and the above-mentioned adhesive film disposed thereon on its side where chips are to be mounted; and a semiconductor device which comprises the above-mentioned adhesive film or the substrate for mounting semiconductor.