Peroxisome proliferator-activated receptors (PPARs) are orphan nuclear hormone receptors that are known to control the expression of genes that are involved in lipid homeostasis and energy balance. PPARs activate gene transcription in response to a variety of compounds, including hypolipidemic drugs. Most of these compounds have high affinity to the ligand-binding domain (LBD) of PPARs and cause a conformational change within PPARs. As a result, the receptor is converted to an activated mode that promotes the recruitment fo co-activators such as the steroid receptor co-activator-1 (SRC-1). Based on the activation mechanism of PPARs (the ligand binding to $PPAR{gamma}$ induces interactions of the receptor with transcriptional co-activators), we performed Western blot and ELISA. These showed that the indomethacin, a $PPAR{gamma}$ ligand, increased the binding between $PPAR{gamma}$ and SRC-1 in a ligand dose-dependent manner. These results suggested that the in vitro conformational change of $PPAR{gamma}$ by ligands was also induced, and increased the levels of the ligand-dependent interaction with SRC-1. Collectively, we developed a novel and useful ELISA system for the mass screening of $PPAR{gamma}$ ligands. This screening system (based on the interaction between $PPAR{gamma}$ and SRC-1) may be a promising system in the development of drugs for metabolic disorders.