Previous studies suggest that β-adrenoceptor stimulation may enhance the cardiac differentiation of mouse embryonic stem (ES) cells. It remains unclear whether the differentiations of ES cells and induced pluripotent stem (iPS) cells rely on similar molecular mechanisms. In addition, no previous studies have shown that human iPS cells express β-adrenoceptors. Therefore, in the present study, we determined the involvement of β-adrenoceptors in the differentiation of human iPS cells into mesodermal progenitor cells. The induction of differentiation of human iPS cells into kinase insert domain receptor (KDR)-positive mesodermal progenitor cells was performed on feeder cells in a differentiation medium with basic fibroblast growth factor (bFGF), bone morphogenetic protein-4 (BMP-4), and activin A. When the iPS cells that were exposed to bFGF, BMP-4, and activin A were treated with L-isoproterenol (a β-adrenoceptor agonist) for 4 days, the expression of KDR was significantly increased compared to that in the cells that were not treated with L-isoproterenol. Pretreatment of the cells with either atenolol (a β1-adrenoceptor antagonist) or ICI-118551 (a β2-adrenoceptor antagonist) significantly inhibited the L-isoproterenol-induced increase in KDR expression. In addition, pretreatment with both H89 (a protein kinase A inhibitor) and SB203580 (a p38 MAPK inhibitor) significantly inhibited the L-isoproterenol-induced increase in KDR expression. Treatment with L-isoproterenol enhanced the phosphorylation of p38 MAPK in human iPS cells exposed to bFGF, BMP-4, and activin A. These results suggest that β-adrenoceptor stimulation in human iPS cells may enhance their differentiation into mesodermal progenitor cells via the activation of either protein kinase A or p38 MAPK.