A play apparatus for children's playgrounds or the like includes a helical spring one end of which is perpendicularly secured to a firm base or ground, and a support member with a seat and a grip is attached to the other end of the helical spring. A base plate is mounted between the base and the helical spring and/or between the support member and the helical spring, wherein the base plate has two grooves with a sector-shaped cross-section corresponding to the cross-section of the helical spring, the grooves being arranged offset and spaced from each other on the level of half of the inclination of the helical spring. A clamping plate which can be clamped against the base plate and also has two grooves corresponding to and arranged opposite of the grooves of the base plate can be clamped against the base plate. The free end of the helical spring is clampable essentially without deformation into the grooves between the base plate and the clamping plate.

A guide mechanism includes a moving member supported by a supporting base frame and moving along a predetermined path with respect to the supporting base frame. A guide projection provided in the moving member is inserted in a guide groove provided in the supporting base frame and moves through the guide groove for guiding the moving member along the path. The guide groove is formed of a pair of thin wall members disposed with a predetermined space therebetween. When the guide projection is in the guide groove, a front end of the guide projection does not contact a bottom surface of the guide groove, and the guide projection slides in a state that a base surface of the guide projection linearly contacts edges of the thin wall members constituting the guide groove.