Transfer chamber

A EFEM comprising:

• a transfer chamber in which a transfer robot is disposed,
• a first fan that forms a downward air flow in the transfer chamber,
• a gas return space that circulates the gas flowing downward in the transfer chamber above the first fan,
• a box that communicates with the transfer chamber,
• openable lids which open and close a gas inflow port through which gas flows into the box and a gas outflow port through which gas flows out of the box configured to switch connection and disconnection of the box to and from the transport chamber,
• wherein a circulation path in which gas circulates is formed by the transfer chamber, the gas return space, and the box, and when the transfer chamber and the box are separated by the openable lids, a shortened circulation path is formed in which the gas circulates without passing through the box.