The present invention relates to a simultaneous modification (hereinafter referred to as " simultaneous reforming "), which is represented by the general formula: R 1a R 2b Q c SiO (4-abc) / 2 and has a number average molecular weight of less than 4,500 and having a long chain alkyl group and a polyoxyalkylene group in the molecule Or an organopolysiloxane obtained by dissolving an organopolysiloxane in an organic solvent.본 발명은, 일반식: R1aR2bQcSiO(4-a-b-c)/2으로 표시되며, 수평균 분자량이 4500 미만이고, 분자 내에 장쇄 알킬 기 및 폴리옥시알킬렌 기를 갖는, 동시 개질된 유기폴리실록산을 포함하는, 표면 처리제 또는 분말 처리제에 관한 것이다.