The present invention relates to an apparatus and a method for shot peening a coil spring, and to a continuous shot peening apparatus and method for a coil spring, in which a coil spring revolves and rotates at the same time during shot peening processing to enable more uniform processing of the coil spring, and a shot peening process and a preparing process thereof are simultaneously performed through simultaneous rotation of a housing in a processing position and a housing in a preparation position, so that the inventive apparatus and method require a simpler configuration and a smaller work space for a shot peening process than those of the prior arts and can perform shot peening of many coil springs in a short period of time.