The National Maritime Museum Cornwall is to lose three of its 34 staff to make it more sustainable.
As part of a restructuring programme to improve its long-term sustainability, the museum has offered staff voluntary redundancies, a spokeswoman said.
The move has come despite the museum registering its strongest financial performance last year.
The spokeswoman said the museum, which is based in Falmouth, anticipated a record 145,000 visitors for the year to 31 March 2016 and had increased attendance by 38 per cent for the year to date.
According to the Charity Commission’s website, the National Maritime Museum Cornwall Trust had an income of almost £2.3m in the year to 31 March 2015 and spent just under £2.6m.
Richard Doughty, director of the NMMC, said: "Despite record-breaking visitor numbers this year and the strongest financial performance ever, we still carry a financial deficit.
"We are determined to make the museum sustainable for the long term and, although change is always unsettling, this is an opportune time to restructure and put in place a plan to reduce shortfalls. We are trying to do this with the minimum of disruption to our staff. However, to protect the future of the museum there will be some job losses.
"This has been a hugely difficult decision and one that has demanded considerable thought. We need to be ready for the new financial year. We have therefore been working closely with our major stakeholders to ensure their ongoing support."
Doughty said the museum would hire a head of commerce, which is a new position at the museum, to "lead the commercial team into a more confident future".
He said: "The museum’s performance is already outstanding among its peers and it is hoped that this restructure will secure an even stronger position, enabling it to continue to deliver as a leader in maritime heritage and a catalyst for regeneration."