Investment Securities (Related Adjustments for Nonmarketable Equity Securities) (Detail) - Nonmarketable equity securities - Measurement alternative - JPY (¥) ¥ in Millions	12 Months Ended
Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2022
Investment Securities [Line Items]
Measurement alternative impairment losses	¥ (11,943)	¥ (8,230)	¥ (4,299)
Measurement alternative downward changes for observable prices	(1,567)	(440)	0
Measurement alternative upward changes for observable prices	882	5,090	¥ 3,067
Cumulative impairment losses	29,569	20,151
Cumulative downward changes for observable prices	2,961	1,393
Cumulative upward changes for observable prices	¥ 58,104	¥ 59,069

Investment Securities [Line Items]

No definition available.

Name:	mufg_InvestmentSecuritiesLineItems
Namespace Prefix:	mufg_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of loss from downward price adjustment on investment in equity security without readily determinable fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 321
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479536/321-10-50-3

+ Details

Name:	us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueDownwardPriceAdjustmentAnnualAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of cumulative loss from downward price adjustment on investment in equity security without readily determinable fair value.

+ References

+ Details

Name:	us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueDownwardPriceAdjustmentCumulativeAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of impairment loss on investment in equity security without readily determinable fair value.

+ References

+ Details

Name:	us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueImpairmentLossAnnualAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of cumulative impairment loss on investment in equity security without readily determinable fair value.

+ References

+ Details

Name:	us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueImpairmentLossCumulativeAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of gain from upward price adjustment on investment in equity security without readily determinable fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 321
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479536/321-10-50-3

+ Details

Name:	us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueUpwardPriceAdjustmentAnnualAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of cumulative gain from upward price adjustment on investment in equity security without readily determinable fair value.

+ References

+ Details

Name:	us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueUpwardPriceAdjustmentCumulativeAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_FinancialInstrumentAxis=mufg_NonMarketableEquitySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ValuationTechniqueAxis=mufg_AlternativeMeasurementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: