Abstract: A glowing mouth guard has a transparent main body, and a transparent glow element for insertion in the main body; the glow element has an outer part formed with several separate holding rooms, which contain respective easily-breakable sealed tubes as well as respective first chemicals therein; the sealed tubes contain respective second chemicals therein; one of both of the chemicals in each holding room of the glow element is a catalytic agent, and the other a luminous chemical, which can produce fluorescent glow through a chemical reaction with the help of the catalytic agent when it is mixed with the agent, such that the holding rooms of the glow element have respective ones of several different-colored fluorescent glows shining.