Fair Value - Additional Information (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
Mar. 31, 2026	Mar. 31, 2025
Disclosure of fair value measurement of assets [abstract]
Percentage of auction rate securities guaranteed by government	95.00%
Transfers out of Level 1 into Level 2 of fair value hierarchy	¥ 0	¥ 0
Transfers out of Level 2 into Level 1 of fair value hierarchy	¥ 0	¥ 0

Percentage of auction rate securities guaranteed by government.

No definition available.

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Namespace Prefix:	hmc_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- References

No definition available.

+ Details

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Namespace Prefix:	ifrs-full_
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- Definition

The amount of transfers out of Level 1 and into Level 2 of the fair value hierarchy of assets held at the end of the reporting period. [Refer: Level 1 of fair value hierarchy [member]; Level 2 of fair value hierarchy [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 13
-IssueDate 2025-01-01
-Paragraph 93
-Subparagraph c
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=13&code=ifrs-tx-2025-en-r&anchor=para_93_c&doctype=Standard
-URIDate 2025-03-27

+ Details

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Namespace Prefix:	ifrs-full_
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Period Type:	duration

- Definition

The amount of transfers out of Level 2 and into Level 1 of the fair value hierarchy of assets held at the end of the reporting period. [Refer: Level 1 of fair value hierarchy [member]; Level 2 of fair value hierarchy [member]]

+ References

+ Details

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Period Type:	duration