| Cover | Sep. 13, 2021 |
| Cover [Abstract] | |
| Entity Registrant Name | MONOPAR THERAPEUTICS INC. |
| Entity Central Index Key | 0001645469 |
| Document Type | 8-K |
| Amendment Flag | false |
| Entity Emerging Growth Company | true |
| Document Period End Date | Sep. 13, 2021 |
| Entity Ex Transition Period | true |
| Entity File Number | 001-39070 |
| Entity Incorporation State Country Code | DE |
| Entity Tax Identification Number | 32-0463781 |
| Entity Address Address Line 1 | 1000 Skokie Blvd |
| Entity Address Address Line 2 | Suite 350 |
| Entity Address City Or Town | Wilmette |
| Entity Address State Or Province | IL |
| Entity Address Postal Zip Code | 60091 |
| City Area Code | 847 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Local Phone Number | 388-0349 |
| Security 12b Title | Common Stock, $0.001 par value |
| Trading Symbol | MNPR |
| Security Exchange Name | NASDAQ |
