Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2024	Jul. 29, 2024
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2024
Document Quarterly Report	true
Document Transition Report	false
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q2
Entity Registrant Name	GEN Restaurant Group, Inc.
Entity Central Index Key	0001891856
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Interactive Data Current	Yes
Securities Act File Number	001-41727
Entity Tax Identification Number	87-3424935
Entity Incorporation, State or Country Code	DE
Entity Address, Address Line One	11480 South Street Suite 205
Entity Address, City or Town	Cerritos
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	90703
City Area Code	(562)
Local Phone Number	356-9929
Title of 12(b) Security	Class A Common stock,par value $0.001 per share
Trading Symbol	GENK
Security Exchange Name	NASDAQ
Class A Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		4,862,230
Class B Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		27,886,912