To improve proper ski performance according to weight of a skier.

This tool is an auxiliary tool for reinforcing elasticity of the rear end part of a V or U-shaped elastic body 10 by integrally providing the V or U-shaped elastic body 10 between a ski plate and a ski at the mounting portion of a ski shoe 40 on the upper surface of the ski plate, providing a square holding member 16 so that the rear end part of the V or U-shaped elastic body 10 may be partially guided to the inside on the upper surface of the ski plate, providing a round auxiliary elastic body 50 on the upper plate of the V or U-shaped elastic body holding part within the square holding member 10 or providing a flat elastic body within the square holding member 16 on an upper plate spring 12 and easily changing the round auxiliary elastic body 50 for other round auxiliary elastic body having proper elasticity according to weight and taste of a skier.