A waterproof structure for outer roof includes a sealing plate fixed to an upper frame so as to form a cabin member, a first elastic sealing member sandwiched between the cabin member and the outer roof, and a second elastic sealing member attached to the outer roof. The first elastic sealing member is sandwiched between the outer roof and the cabin member to form a first sealing portion that seals the inner space of the cabin from the outside. A sealing site of the second sealing member is pressed against an outward extending region to form a second sealing portion that seals the inner space of the cabin from the outside at a position outside the first sealing portion. The present invention can enhance waterproof property as well as quality in outer appearance.