A safety apparatus of an automatic door may include a body mounted with an entrance, a door slidably mounted on the body and opening or closing the entrance, and a safety device including a safety part slidably mounted at a side of the door and an elastic part mounted at the side of the door to elastically support the safety part, wherein the safety part may be slidably mounted on an upper portion and a lower portion of the side of the door, respectively, and includes upper and lower moving members slidably mounted on the side of the door and elastically supported by the elastic part, and a rotating member rotatably mounted between the upper and lower moving members.