Physical inactivity due to prolonged sedentary behavior induces obesity. Therefore, we investigated whether housing mice in small cages to mimic sedentary behavior induced obesity and whether dietary oleamide (cis-9,10-octadeceneamide) suppressed the induced obesity. A single oral administration of oleamide (50 mg/kg) to mice resulted in the accumulation of the exogenous oleamide in abdominal visceral fat. Next, mice were housed in small cages and oleamide (50 mg/kg/d) was orally administered for 12 weeks. Housing mice in small cages impaired glucose tolerance and increased food efficiency. It also increased body weight and abdominal fat mass. Dietary oleamide improved the impairment and inhibited their increases in mice housed in small cages. Furthermore, dietary oleamide suppressed the mRNA expression of inflammation-related factors in abdominal fat of mice housed in small cages. Hence, these results indicate that although housing mice in small cages induces obesity and increases abdominal fat mass, dietary oleamide suppresses the obesity.