Abstract: A coil spring device includes: a main body spring and an insulator, the insulator is provided with a support groove which extends around a coil axis and into which a lower end portion of the main body spring is fitted, the lower end portion of the main body spring adheres to an inner surface of the support groove, the inner surface of the support groove is provided with a plurality of spacer protrusions which support an outer peripheral surface of a wire rod, a plurality of adjacent spacer protrusions adjacent to an open end edge of the support groove of the plurality of spacer protrusions each includes a pair of side wall surfaces extending toward the open end edge and are provided at intervals therebetween in an extension direction of the open end edge in a plan view of a part including the open end edge in the inner surface of the support groove, and inclination angles of the side wall surfaces adjacent to each other in the extension direction with the interval therebetween with respect to an orthogonal di

Abstract: A coil spring includes a main body spring and an insulator, the insulator is provided with a support groove which extends around a coil axis and into which a lower end portion of the main body spring is fitted, a lower end portion of the main body spring adheres to an inner surface of the support groove, the inner surface of the support groove is provided with a plurality of spacer protrusions which support an outer peripheral surface of a wire rod, the support groove extends in an angle range of 180° or more and 360° or less around the coil axis, and a ratio of a volume of the spacer protrusions occupying a gap between the inner surface of the support groove and the outer peripheral surface of the wire rod at a center portion in the gap in a circumferential direction around the coil axis is larger than that at the other portions in the gap in the circumferential direction.