When not in use, it can be folded and stored and stored in a bulky manner. At the same time, it can be easily transformed into a three-dimensional cap shape when used, and quickly mounted, and can also be used as other functional products such as cushion pads and tubes. A simple protective cap is provided. The simple protective cap is provided with a vortex-shaped portion composed of a plurality of vortex-shaped cutouts that are directed outward from the center of the plate-like synthetic resin foam material having a predetermined thickness and penetrate in the thickness direction, wherein the plurality of vortex-shaped cutouts, The starting end is arranged on the circumference of a predetermined radius from the center in the center of the foam material, and the end is arranged at a position exceeding 360 degrees from the starting end, forming a vortex line exceeding one layer.
展开▼
