To provide a safety cabinet avoiding infection by making proper judgment on the clogging state of an exhaust HEPA filter of the safety cabinet to maintain an air barrier.

The safety cabinet 1 comprises an exhaust system for discharging air out of a work space 3 through the exhaust HEPA filter 4 by a blowing means 6, a front face shutter 9 formed in the front face of the work space and the front face opening connected with the work space below the front face shutter, and is further provided with an opening size detecting unit for detecting the opening of the shutter and a wind speed sensor 20 installed in the leeward side or the windward side of the exhaust HEPA filter. The clogging state of the exhaust HEPA filter is judged on the basis of change in air volume obtained by using the wind speed of the wind flowing through the exhaust HEPA filter and the size of the front face opening below the front face shutter.