A coil spring reduces Hertzian stress on a first turn and bending stress on a coil end.A coil end 11 is shifted in a diametral outer or inner direction of a coil spring relative to the first turn 13, to form a vertical gap between the coil end 11 and the first turn 13 in a free state without load on the coil spring. Due to the gap, the coil spring including the coil end 11 and first turn 13 can be entirely processed by shot peening as well as the remaining portion. The first turn 13 receives a combination of torsional stress and Hertzian stress (contact stress). Since the coil end 11 that receives high Hertzian stress is shifted in a diametral outer or inner direction of the coil spring relative to the first turn 13, a contact point on the first turn 13 is shifted in the diametral outer or inner direction to reduce the torsional stress on the first turn 13. The shift and gap formed between the coil end 11 and the first turn 13 are effective to prevent excessive bending stress and breakage of the coil end 11 when the coil end 11 and first turn 13 are repeatedly engaged and disengaged in the gap.