A compressive residual stress portion (50) having a compressive residual stress from a surface of a wire (40) to a first depth (D1) is formed between end turn portions (12a, 12b) of a coil spring (12). The end turn portion (12a) includes a first portion (12a 1 ), a second portion (12a 2 ), and a third portion (12a 3 ). The first portion (12a 1 ) is always in contact with a spring seat irrespective of a load applied to the coil spring (12). The second portion (12a 2 ) contacts the spring seat when the load applied to the coil spring (12) is large, and is separated from the spring seat when the load is small. The third portion (12a 3 ) is always separated from the spring seat irrespective of the magnitude of the load. In the end turn portion (12a), in a region including the second portion (12a 2 ), a deep residual stress portion (51) is formed by ultrasonic shot peening. The deep residual stress portion (51) has a compressive residual stress from a surface of the wire (40) to a second depth (D2) deeper than the
