In many biomedical devices such as catheters and diagnostic sensors, blood compatibility is required. The best way to control this property is to prevent or drastically reduce the adsorption of proteins. Poly(ethylene glycol) terminated amine at both terminals, NH2-PEG-NH2, is immobilized on a commercially pure titanium, a 316L austenitic stainless steel, and a cobalt-chromium-molybdenum alloy with immersion or electrodeposition. Chemical bonding states at the interface and orientation of PEG molecules were characterized using X-ray photoelectron spectroscopy, glow discharge optical emission spectroscopy, and Fourie-transformed infrared spectrometer with a reflection absorption spectrometer. As a result, NH2-PEG-NH2 was immobilized onto metal surface as a U-shape mainly with stable NHO bonding in electrodeposition. In the case of electrodepostion, the concentration of active surface hydroxyl groups on surface oxide film played an important role in the immobilization.