To provide a draft chamber in sections the knocked-down parts of which can be assembled and used, when required, near an existing laboratory instrument on a top plate of a laboratory table or at another place, which has absolute minimum functions though it has a simple structure and is inexpensive and can be used even in comparatively safe laboratory work in which the use of the draft chamber is not obligated up to now.

A side frame body 6 having a square side view is arranged on both sides. Four corners of one of side frame bodies are connected detachably to those of the other of side frame bodies by using upper connection bars 7 and lower connection bars to form a frame 1. A decorative frame body 9 having a square side view is fit detachably to the outside of the side frame body while interposing a side plate 10 between them to form a side panel 2. A rear panel 3 to be opened by a blast from the internal treatment space is arranged in the space to be formed by the rear end of one of side frame bodies, that of the other of side frame bodies, the upper connection bar and the lower connection bar. An opening/closing door panel 4 is arranged in the space to be formed by the front end of one of side frame bodies, that of the other of side frame bodies, the upper connection bar and the lower connection bar. A top cover 5 is placed and connected detachably onto the upper surface of the frame.