Karuigzawa Ohga Hall, Concert hall in Karuizawa, Japan.

Karuizawa Ohga Hall is a concert hall in Karuizawa, Nagano Prefecture, completed by Kajima Corporation in December 2004 and opened on 29 April 2005. The long, low building has a dark grey shallow-pitched roof with a square glass-pyramid lantern at its centre and a row of small skylights along the wings; a wide band of glazing runs above a dark base, facing a pond and trees. The hall itself is pentagonal, seating 784, with a 150 m² stage and a ceiling 14.5 m at its highest point.

Sony honorary chairman and vocalist Norio Ohga funded the hall with a 1.6 billion yen donation, fulfilling his wife, pianist Midori Matsubara's, wish for a quality hall in Karuizawa. Designed and built by Kajima Corporation, it opened on 29 April 2005. Karuizawa town ran it until 1 October 2006, when the Karuizawa Ohga Hall Foundation took over.

The hall is named after Norio Ohga, the Sony honorary chairman and trained singer who funded it with a 1.6 billion yen donation from his retirement pay, at the wish of his wife, pianist Midori Matsubara. Ohga said he hoped Karuizawa would become a music town like Salzburg or Lucerne. Some standing places on the second-floor balcony remain, kept so young people can hear good music cheaply.

The hall stands at Karuizawa East 28-4, next to Yagasaki Park and Myosho-ji temple, on a site of about 6,500 m2 with a 1,800 m2 lawn garden. It is a two-storey building 18.9 m high, so the 784 seats are reached on foot between two levels; four wheelchair spaces are provided. The second-floor seats were fitted with chairs in January 2010, leaving 38 standing places on the wooden rail.

The hall's pentagonal shape was chosen so sound reaches every seat evenly. Its second-floor bench standing area, kept at the wish of donor Norio Ohga, lets young people hear music at low cost; in 2010 chairs were added, reducing seats from 140 to 124.