An attachment structure for an electronic component accommodation box including a vibration proof structure includes a damping structure between a vehicle body side attachment member and a casing in which at least one electronic component is mounted. The damping structure includes first sliding portions, second sliding portions, and damping members interposed between the first sliding portions and the second sliding portions. The damping members generate sliding resistance between each of the first sliding portions and each of the second sliding portions when the casing moves relative to the vehicle body side attachment member.