v3.26.1
Cover Page
 12 Months Ended
Mar. 31, 2026
shares
Document Information [Line Items]  
Document Type 20-F
Amendment Flag false
Document Period End Date Mar. 31, 2026
Document Fiscal Year Focus 2026
Document Fiscal Period Focus FY
Entity Registrant Name Mizuho Financial Group, Inc.
Entity Central Index Key 0001335730
Current Fiscal Year End Date --03-31
Entity Well-known Seasoned Issuer Yes
Entity Current Reporting Status Yes
Entity Voluntary Filers No
Entity Interactive Data Current Yes
Document Annual Report true
Document Transition Report false
Document Shell Company Report false
Entity Shell Company false
Entity Filer Category Large Accelerated Filer
Entity Emerging Growth Company false
Entity Common Stock, Shares Outstanding 2,489,848,594
Document Accounting Standard U.S. GAAP
Entity File Number 001-33098
Entity Incorporation, State or Country Code M0
Document Registration Statement false
Entity Address, Address Line One 1-5-5 Otemachi
Entity Address, City or Town Chiyoda-ku
Entity Address, Postal Zip Code 100-8176
Entity Address, Country JP
ICFR Auditor Attestation Flag true
Auditor Name Ernst & Young ShinNihon LLC
Auditor Firm ID 789
Auditor Location Tokyo, Japan
Document Financial Statement Error Correction [Flag] false
American depositary shares  
Document Information [Line Items]  
Security Exchange Name NYSE
Title of 12(b) Security American depositary shares, each of which represents two shares of common stock
Trading Symbol MFG
Common Stock  
Document Information [Line Items]  
Title of 12(b) Security Common Stock, without par value*
No Trading Symbol Flag true
Business Contact  
Document Information [Line Items]  
Contact Personnel Name Hikaru Osuga
Entity Address, Address Line One 1-5-5 Otemachi
Entity Address, City or Town Chiyoda-ku
Entity Address, Postal Zip Code 100-8176
Entity Address, Country JP
City Area Code 81-3
Local Phone Number 5224-1111