Roller assembly, casting apparatus, and roller separating method for same

Provided is a roller assembly which includes: a supporter configured to rotatably support a roller disposed in a movement path of a to-be-treated material; a fixed shaft attached to a rear surface of the supporter and having at least a stretchable portion; a body attached to the rear surface side of the supporter so as to surround the fixed shaft; and a plunger attached so as to connect the body and the fixed shaft and formed so that at least a portion thereof advances and retreats with respect to the movement path, a casting device provided with the roller assembly, and a roller separating method, wherein the roller assembly is capable of separating the roller from the movement path during emergency.