An earplug, which is inserted and worn inside a person's ear canal, consists of a main guide body provided with a compression portion, a supporting stem provided with an air passage and used to support the main guide body, and a filler material provided with plasticity that fills the compression portion. A filling cavity is provided inside the compression portion that interconnects with the air passage and enables filling with the filler material, and causes an air chamber that connects to the air passage to form inside the compression portion, enabling the compression portion to form an original state. The compression portion is in a compressed state when pressed and constricted, and air circulating in the air passage is used to cause changes in the compression portion between its original state and compressed state, which enables enhancing comfortability when wearing the earplug.
