Peroxisome proliferator-activated receptors (PPARs) are nuclear hormone receptors that are activated by fatty acids and their derivatives. PPARs consist of three isotypes named PPAR alpha (NR1C1), PPAR beta/delta (NR1C2) and PPAR gamma (NR1C3) in vertebrates. Each of them is encoded in a separate gene and binds fatty acids and eicosanoids. Although each isotype fulfills distinct functions, PPARs function not only as an important fatty acid sensor that regulate lipid, carbohydrate and amino acid metabolism but also play an important role in various signaling pathways (immunity, inflammation, apoptosis and cell differentiation). Dysfunction of PPAR-mediated signals leads to various diseases such as diabetes, obese, hyperlipidemia, inflammation and cancer. Importantly, magnesium appears to play a pivotal role in regulating the PPAR-mediated signaling pathways as a key cofactor in the protein phosphorylation. Therefore, restrict control of magnesium concentration in the body appears to be very important for protection for these diseases. In this review, I focus on emerging knowledge about relationship between PPAR-mediated signals and magnesium.