| Document and Entity Information | Oct. 14, 2021 |
| Document and Entity Information [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Oct. 14, 2021 |
| Entity File Number | 001-34852 |
| Entity Registrant Name | RARE ELEMENT RESOURCES LTD. |
| Entity Incorporation, State or Country Code | A1 |
| Entity Tax Identification Number | 00-0000000 |
| Entity Address, Address Line One | P.O. Box 271049 |
| Entity Address, City or Town | Littleton |
| Entity Address, State or Province | CO |
| Entity Address, Postal Zip Code | 80127 |
| City Area Code | 720 |
| Local Phone Number | 278-2460 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001419806 |
| Amendment Flag | false |
