Chief Executive Tatsufumi Sakai is among those to go.
At a news conference Friday (November 26) he said he had to take responsibility:
"Due to two system failures in the past and a series of system failures since February, we couldn't properly fulfil our task as a financial institution to play a role in social infrastructure. It is very regrettable that it has caused trust problems in Japan's payment system."
Mizuho has been plagued by a series of problems.
This year saw eight major system glitches, despite a $3.6 billion overhaul of the bank's IT in 2019.
During one outage the lender failed to comply with anti-money laundering procedures for overseas remittances.
That was a major embarrassment for Tokyo, which has been trying to beef up its safeguards against such crimes.
Earlier Friday Mizuho was reprimanded by Japan's finance ministry and its banking watchdog.
The ministry cited a range of problems, including a lack of knowledge of foreign exchange laws among executives.
