An electronic apparatus includes a circuit board; a housing which incorporates the circuit board and includes, on the bottom surface of the housing, an opening, through which a portion of one surface of the circuit board is visible, and a fastening hole; an electronic component mounted in the opening and accommodated in the housing; and a fastening member inserted into the fastening hole and fixing the housing. The housing has a rib formed along the entire circumference of the opening, and the rib extends from the circumferential edge of the opening toward the circuit board and prevents the fastening member that has fallen into the opening from entering the housing.