PURPOSE: To provide a footwear, which simply issues a warning of the approach of thunderclouds, by a method wherein a grounding member, a conductive member between the footwear and the foot, a detecting means electric potential difference and an approach-determining means for the thunderclouds are provided in a shoe.

CONSTITUTION: A shoe 1 has a foot-holding part 3, a tread part 5, a grounding member 7, a conductive member 9 between the shoe and the foot, a detect means 11 for electric potential difference, an approach-determining means 13 for thunderclouds, an approach signal-outputting means 15 for the thunderclouds and an electric power-supplying means 17. The foot-holding part 3 is formed of an electrical insulating material and the insulating property between the body and the ground is ensured. The tread part 5 has an outsole 18 and a heel 19. The grounding member 7 is composed of a conductive material and has a metallic plate 21 and spikes 23. The conductive member 9 is formed of a conductive material and is located a a place where it is brought into contact with the sole of the foot. The detecting means 11 is connected to both the grounding member 7 and the conductive member 9 and detects the electric potential difference between them. The approach-determining means 13 outputs the approach signal of the thunderclouds when the output of the detecting means 11 is beyond a definite value.