| Document And Entity Information - USD ($) | 12 Months Ended | ||
| Dec. 31, 2023 | Apr. 29, 2024 | Jun. 30, 2023 | |
| Document Information Line Items | |||
| Entity Registrant Name | NKGen Biotech, Inc. | ||
| Document Type | 10-K/A | ||
| Current Fiscal Year End Date | --12-31 | ||
| Entity Common Stock, Shares Outstanding | 22,494,671 | ||
| Entity Public Float | $ 62,842,555 | ||
| Amendment Flag | true | ||
| Amendment Description | This Amendment No. 1 (this “Amendment”) amends the Annual Report on Form 10-K for the year ended December 31, 2023 of NKGen Biotech, Inc. (the “Company”), filed with the Securities and Exchange Commission (the “SEC”) on April 16, 2024 (the “Original Form 10-K”). The purpose of this Amendment is solely to amend Part III, Items 10 through 14 of the Original Form 10-K to include information previously omitted from the Original Form 10-K in reliance on General Instruction G(3) to Form 10-K which permits the above-referenced Items to be incorporated in the Annual Report on Form 10-K by reference from a definitive proxy statement, if such proxy statement is filed no later than 120 days after December 31, 2023. At this time, the Company is filing this Amendment to include Part III information in our Annual Report on Form 10-K because we do not intend to file a definitive proxy statement within 120 days of December 31, 2023. Accordingly, Part III of the Original Form 10-K is hereby amended and restated as set forth herein. The information included herein as required by Part III, Items 10 through 14 of Form 10-K is more limited than what is required to be included in the definitive proxy statement to be filed in connection with our annual meeting of stockholders. Accordingly, the definitive proxy statement to be filed at a later date will include additional information related to the topics herein and additional information not required by Part III, Items 10 through 14 of Form 10-K.The reference on the cover page of the Original Form 10-K to the incorporation by reference of our definitive proxy statement into Part III of the Original Form 10-K is hereby deleted.In addition, this Amendment appends Exhibits 4.1, 4.2, 4.3 and 97.1 which were inadvertently omitted from the Original Form 10-K.Except as stated herein, this Amendment does not reflect events occurring after the filing of the Original Form 10-K and no attempt has been made in this Amendment to modify or update other disclosures as presented in the Original Form 10-K. | ||
| Entity Central Index Key | 0001845459 | ||
| Entity Current Reporting Status | Yes | ||
| Entity Voluntary Filers | No | ||
| Entity Filer Category | Non-accelerated Filer | ||
| Entity Well-known Seasoned Issuer | No | ||
| Document Period End Date | Dec. 31, 2023 | ||
| Document Fiscal Year Focus | 2023 | ||
| Document Fiscal Period Focus | FY | ||
| Entity Small Business | true | ||
| Entity Emerging Growth Company | true | ||
| Entity Shell Company | false | ||
| Entity Ex Transition Period | false | ||
| ICFR Auditor Attestation Flag | false | ||
| Document Annual Report | true | ||
| Document Transition Report | false | ||
| Entity File Number | 001-40427 | ||
| 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 Interactive Data Current | Yes | ||
| Document Financial Statement Error Correction [Flag] | false | ||
| Auditor Name | Ernst & Young LLP | ||
| Auditor Location | Irvine, California | ||
| Auditor Firm ID | 42 | ||
| Common Stock, $0.0001 par value per share | |||
| Document Information Line Items | |||
| Trading Symbol | NKGN | ||
| Title of 12(b) Security | Common Stock, $0.0001 par value per share | ||
| Security Exchange Name | NASDAQ | ||
| Warrants, each whole warrant exercisable for one share of Common Stock at an exercise price of $11.50 per share | |||
| Document Information Line Items | |||
| Trading Symbol | NKGNW | ||
| 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 | ||
| Security Exchange Name | NASDAQ |
