Nishikasugai (西春日井郡 Nishikasugai-gun?) is a district located in Aichi Prefecture, Japan.
Located on the central Owari Region. The population is 22,194 people; the total area is 10.20 km² (as of March 1, 2007). Currently the district has the town of Toyoyama.
During the old days, the district extended as far as Nagoya Castle, but since Taisho Era to the 1950s, most of the areas were merged into the city of Nagoya.
Recently, there were proposals to turn the entire district into a city but the merger was killed due to differences of opinion. After the merger was killed, the towns of Kiyosu, Shinkawa and Nishibiwajima merged in 2005 (City of Kiyosu). Again in 2006, the towns of Nishiharu and Shikatsu merged into (City of Kitanagoya). And most recently in 2009, the town of Haruhi merged into Kiyosu. As a result of this merger, the district has only the town of Toyoyama.
J-Air, a subsidiary of Japan Airlines, is headquartered in Toyoyama, Nishikasugai District, in the Nagoya Airfield Terminal Building.Nakanihon Air Service, a general aviation operator, is also located in Toyoyama on the airport grounds.