An electronic control device according to an embodiment of the present disclosure comprises a lower cover including a side wall with a first coupling portion and a second coupling portion; a circuit board arranged inside the side wall of the lower cover and having on the upper surface thereof a button; a middle cover provided with a third coupling portion coupled to the first coupling portion and a first button hole, and coupled to the lower cover by coupling of the third coupling portion to the first coupling portion; a button cover arranged on the upper surface of the middle cover, covering the first button hole, and having a protrusion portion; and an upper cover including a side wall provided with a fourth coupling portion coupled to the second coupling portion, the upper cover provided with a second button hole, and covering the button cover and the middle cover.