Cover - shares	6 Months Ended
	Jun. 30, 2024	Sep. 12, 2024
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2024
Document Transition Report	false
Entity File Number	001-40427
Entity Registrant Name	NKGen Biotech, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	86-2191918
Entity Address, Address Line One	3001 Daimler Street
Entity Address, City or Town	Santa Ana
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92705
City Area Code	(949)
Local Phone Number	396-6830
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		35,362,376
Current Fiscal Year End Date	--12-31
Entity Central Index Key	0001845459
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q2
Amendment Flag	false
Common Stock
Document Information [Line Items]
Title of 12(b) Security	Common Stock, $0.0001 par value per share
Trading Symbol	NKGN
Security Exchange Name	NASDAQ
Warrant
Document Information [Line Items]
Title of 12(b) Security	Warrants, each whole warrant exercisable for one share of Common Stock at an exercise price of $11.50 per share
Trading Symbol	NKGNW
Security Exchange Name	NASDAQ