One of the purposes of the present invention is to provide an addition-curable silicone composition which provides a cured product having good performance at a low temperature and excellent resistance to a temperature change, and to provide a semiconductor device having a high reliability, whose semiconductor element is encapsulated with a product obtained by curing the addition-curable silicone composition. Thus, an addition-curable silicone resin composition comprising (A) a branched organopolysiloxane represented by the following formula (1): wherein a is an integer of from 2 to 100, b is an integer of from 5 to 100, c is an integer of from 5 to 100, 0.03≤a/(a+b)