Disclosed therein are a pulley assembly for a compressor and a manufacturing method of the same, which can prevent possible damages during processing and is fit for high-temperature environment because a pulley is made of magnesium alloy.The pulley assembly includes: a cylindrical hollow pulley made of magnesium alloy; an inner ring formed integrally with the pulley by insert injection molding, the inner ring being fixed to the inner circumferential surface of the pulley and made of a different material from the pulley; and a bearing forcedly pressed and fixed to the inner circumferential surface of the inner ring.