TSB Chief Paul Pester is to step down after seven years in charge, in the wake of a major IT failure at the bank.
The bank is still struggling to get its IT systems to work properly.
On Monday, it apologised to customers who faced disruption to their online and mobile banking over the weekend.
Following Mr Pester's departure, TSB chairman Richard Meddings will take on the role of executive chairman until a new chief executive is appointed.
Mr Meddings said: "Although there is more to do to achieve full stability for customers, the bank's IT systems and services are much improved since the IT migration. Paul and the Board have therefore agreed that this is the right time to appoint a new CEO for TSB."
Nicky Morgan, chair of the Treasury Committee, said she felt Mr Pester's decision was the correct one.
"Since the IT problems at TSB began, Paul Pester set the tone for TSB's complacent and misleading public communications," she said.
"In this light, it is right that he is stepping down, but the committee remains concerned about the continuing problems at TSB, including unacceptable delays in compensating customers who have been badly let down."
BBC News.