An electronic control device for suppressing mixing of foreign substances includes a control board including a heat generation component, a housing, a support member that is provided in the housing and supports the board, a heat radiation fin on a surface opposite to a surface of the support member on which the control board is supported, an air cooling fan that intersects an extension direction of the heat radiation fin, and blows wind to the heat radiation fin, a wall portion between the control board and the air cooling fan, and extending from the support member toward the control board, a wiring passage at a top end of the wall portion, a wiring that is laid in the wiring passage, and electrically connects the air cooling fan and the control board, and a cover that covers the housing, and includes a protrusion fitted in the wiring passage.