[Problem] To provide an agent for enhancing antibody production ability. A culture supernatant preparation containing a culture supernatant of mesenchymal stem cells as an active ingredient for enhancing antibody production ability. An example of a mesenchymal stem cell is a human mesenchymal stem cell, and a mesenchymal stem cell obtained by culturing a mesenchymal stem cell using a serum-free medium is more preferable. This formulation is used, for example, to enhance the ability of the administered subject to produce IgA or IgG antibodies. [Selection] Figure 1【課題】抗体産生能力を高める剤の提供。【解決手段】間葉系幹細胞の培養上清を有効成分として含む抗体産生能力を増強するための培養上清製剤。間葉系幹細胞の例は，ヒト間葉系幹細胞であり，間葉系幹細胞が，無血清培地を用いて培養された間葉系幹細胞がより好ましい。この製剤は，たとえば，投与された対象のＩｇＡ抗体又はＩｇＧ抗体の産生能力を増強するために用いられる。【選択図】図１
