access restriction; entry restriction
Refers to limiting or controlling entry to a room, building, or indoor space, often for security, capacity, or privacy reasons.
This area is under access restriction, so only authorized personnel may enter.
Access to the server room is restricted.
立ち入り禁止 is a stronger, more absolute prohibition (no entry), while 入室制限 implies controlled or limited access rather than a complete ban.
Compound of 入室 (entering a room) and 制限 (restriction, limitation).