A safety cabinet which can prevent contaminated air from leaking from a working space through the periphery of a front shutter, and which can prevent outside air from entering the working space has a peripheral structure part surrounding the working space formed with air suction ports in a part opposed to the inner surface of the front shutter connected to a negative pressure passage formed outside of the working space. The negative pressure passage guides air sucked through the air suction ports from the inside and the outside of the working space, toward a filter for purification of the air.