The gunbai (軍配, short for 軍配団扇 gunbai uchiwa) is a type of Japanese war fan.
Gunbai were used by samurai officers in Japan to communicate commands to their troops, and were solid, not folding, and usually made of wood, wood covered with metal, or solid metal.
It is also a key accessory of a gyoji in professional sumo. One use is at the end of a bout, when the gyoji points the gunbai at the wrestler he judges to be the victor. Reflecting this, the gyoji's decision itself is often informally referred to as a "gunbai". If this is called into question and the shimpan (umpires) hold a consultation, a decision to uphold the gyoji's judgement is announced as gunbai-dori (軍配通り), literally "according to the gunbai", while a decision to overturn it is gunbai sashichigae (軍配差し違え), literally "gunbai miss-pointed."