An adjuvant composition of the present invention contains lauryl alcohol and propylene glycol. Contents of the lauryl alcohol and the propylene glycol are 0.5 to 25% by mass and 8.0 to 99.5% by mass, relative to the total mass of the adjuvant composition, respectively. The lauryl alcohol is dissolved, and the adjuvant composition is used for transdermal or transmucosal administration.本發明之佐劑組成物係含有月桂醇及丙二醇之佐劑組成物，以佐劑組成物總質量基準，月桂醇及丙二醇之含量分別為0.5~25質量%及8.0~99.5質量%，月桂醇已溶解，且為經皮或經黏膜投藥用。
