To provide an electromagnetic wave prevention device, which generates powerful negative ions from an obsidian at a low cost, is capable of compactly being mounted to a variety of products with a ceramics plate or ion ball having numerous holes, and contributes to health promotion, natural healing energy promotion, clarification of cells and blood, resistance promotion, autonomic nervous system modulation, sympathetic nervous system activation, skin disease, skin whitening, cellular activation or the like with its much generated negative ions.

Negative ions generated from an obsidian produced in Wada ghat of Nagano prefecture, tourmaline ore, and phosphate ore ion ball are measured, which shows that 2,700/cc negative ions per ball (10 mm) are generated. 8,000 or more negative ions per 1 cm3 are measured for 20 seconds from the electromagnetic prevention device equipped with the powerful negative ion ball 2. A blue light 5 is portable so as to illuminate from beneath, which give a good effect on a human body from the viewpoint of heeling.