The purpose of this study was to clarify the effects on oxidative stress and the kidney tissues of obese type2 diabetes model rats when catechins were ingested. 5-week-old obese type 2 diabetes model male rats were kept for 4 weeks. A normal diet was fed to a control group (n=6), while an experimental catechin group (n=6) was fed catechin. Posterior subcutaneous abdominal fat weight and oxidative stress were measured, and kidney tissues were observed. Posterior subcutaneous abdominal fat weight and oxidative stress were significantly lower in the catechin group than in the control group. In the kidney tissues, the mesangial region in the control group was larger than in the capillary space, and the glomerulus was lobulated. The mesangial area in the catechin group was almost equivalent to the capillary space. Ingestion of catechin in obese type 2 diabetes model rats reduced fat accumulation and oxidative stress. It has also been suggested that catechin suppresses damage to mesangial cells in kidney tissue. Catechin intake likely suppresses oxidative stress and diabetic nephropathy inflammation, and it could be useful for the prevention of diabetes.