To prevent buckling of a compression coil spring during elongation and contraction without flatly machining the coil end portion of the compression coil spring.

In the structure of a spring shoe, the end face 21A of the coil end portion 21 at one end side of the compression coil spring 20 is tilted by a winding angle of a wire with respect to the axis of the spring. At least two saw tooth shape surfaces 32 are provided on a periphery of a bearing surface 31 of a cap bolt 30, which bearing surface supports the compression coil spring 20. Each of the saw tooth shape surfaces 32 is provided with a slant spring supporting surface 32A for supporting the coil end portion 21 at one end side of the compression coil spring 20, and a locking surface 32B which is continued from the spring supporting surface 32A and is lockingly engaged with one end of the coil end portion 21 of the compression coil spring 20 in the winding direction of the spring 20.