To prevent the damage of a wall and wallpaper owing to exhaust gas by providing a discharge part with an exhaust discharge direction changing member for changing an exhaust discharge direction into the upward one.

The surplus space 38 of a recessed step part 33 is formed in the rear part of the rear side part of an opening part frame 31 including the discharge port 37, it is made to correspond to the discharge port 37 in its center part and the exhaust discharge direction changing member 39 is mounted. The member 39 is formed by a bottom surface board 39c, a rear surface board 39d and side surface boards 39e in the upper part of front and rear leg boards 39a and 39b. Then it is inserted between the discharge port 37 and the rear end wall surface 33a of the recessed step part 33 on a top plate 3 by slight force-fitting and fixed. A front surface opening part is made to communicate with the discharge port 37. The upper surface of the bottom surface board 39 in the exhaust discharge direction changing member 39 is made to be on the same surface with the inner bottom surface of the discharge port 37. Thus, vapor to be discharged is discharged upward as shown by an arrow B and the damage is prevented by preventing abutment on the wall W.