A coil spring made of an element wire that is coiled and to be arranged between a movable part and a stationary part: a first end of the element wire defined between a tip and a first turn of the element wire being arranged on the movable part, being continuous to a first turn of the element wire, and being shifted in one of diametral inner and outer directions of the coil spring relative to the first turn, to form a horizontal shift in a diametral direction of the coil spring and a vertical gap (t) in an axial direction of the coil spring between the first end and the first turn when the coil spring is in a free state without load, said gap (t) being defined on a line passing through sectional centers of the first end and the first turn, the first end defined between the tip and the first turn of the element wire being shifted in one of diametral inner and outer directions of the coil spring relative to the first turn such that the first end of the element wire over its whole length between the tip and the first turn overlaps partly the first turn in an axial direction of the coil spring, and the first end of the element wire having a thickness gradually decreasing toward the tip, characterized in that the first end defined between the tip and the first turn of the element wire is shifted in one of diametral inner and outer directions of the coil spring relative to the first turn such that when the coil spring is repeatedly compressed with a maximum amount so that the first end comes in contact with the first turn at a contact point, the contact point is shifted in one of diametral inner and outer directions of the coil spring according to the horizontal shift in a diametral direction of the coil spring when the coil spring is in a free state without load, and the size of the shift of the first end relative to the first turn of the element wire is 1/2 of the diameter of the element wire or smaller. a first end of the element wire defined between a tip and a first turn of the element wire being arranged on the movable part, being continuous to a first turn of the element wire, and being shifted in one of diametral inner and outer directions of the coil spring relative to the first turn, to form a horizontal shift in a diametral direction of the coil spring and a vertical gap (t) in an axial direction of the coil spring between the first end and the first turn when the coil spring is in a free state without load, said gap (t) being defined on a line passing through sectional centers of the first end and the first turn, the first end defined between the tip and the first turn of the element wire being shifted in one of diametral inner and outer directions of the coil spring relative to the first turn such that the first end of the element wire over its whole length between the tip and the first turn overlaps partly the first turn in an axial direction of the coil spring, and the first end of the element wire having a thickness gradually decreasing toward the tip, characterized in that the first end defined between the tip and the first turn of the element wire is shifted in one of diametral inner and outer directions of the coil spring relative to the first turn such that when the coil spring is repeatedly compressed with a maximum amount so that the first end comes in contact with the first turn at a contact point, the contact point is shifted in one of diametral inner and outer directions of the coil spring according to the horizontal shift in a diametral direction of the coil spring when the coil spring is in a free state without load, and the size of the shift of the first end relative to the first turn of the element wire is 1/2 of the diameter of the element wire or smaller.