To provide a safety cabinet corresponding to the height of a worker who works in the safety cabinet, that is, the safety cabinet which allows various outside bacteria not to invade a work space even if an opening size of a front face shutter is changed, and microbes and bacteria in a working chamber not to discharge outside.

The opening size of the front face shutter is detected. Corresponding to the size, the blowing wind velocity of a clean air current inside the working chamber, and the inflow wind velocity of a front face opening are changed to a predetermined wind velocity able to maintain a physical isolation capability to prevent any infection.