A board member on the Peninsula Symphony of Northern California received an overdraft notice from the bank last week, which led him to discover the money missing from the symphony's account.
He called police in Los Altos, where they are based. They have launched a criminal investigation.
No suspects have been named but the group's executive director recently resigned. The symphony didn't say why he left.
"It represents substantially all of the assets of the organization," symphony spokesperson Larry Kamer said. "Unfortunately it's a serious event, but fortunately it's unique. And we're going to do everything we can to make sure nothing like this can ever happen again."
Kamer says the missing funds include income from donations, ticket sales, investment interest and operating revenue, with the money going to pay orchestra member's salaries, marketing and other expenses.
He notes that no one knows how the symphony's funds were depleted, "Exactly where the money was taken is still being investigated," Kamer said.
The 85 member group has been around for 65 years.
The symphony is determined to continue its upcoming concert season, which starts later this month. They're calling on community members and music lovers to help them recoup some of the funds that were stolen.
(Bay City News contributed to this report)