XML 49 R1.htm IDEA: XBRL DOCUMENT v3.26.1
Cover - $ / shares
 12 Months Ended
Dec. 31, 2025
Apr. 30, 2026
Entity Addresses [Line Items]    
Document Type 20-F  
Amendment Flag false  
Document Registration Statement false  
Document Annual Report true  
Document Transition Report false  
Document Shell Company Report false  
Document Period End Date Dec. 31, 2025  
Document Fiscal Period Focus FY  
Document Fiscal Year Focus 2025  
Current Fiscal Year End Date --12-31  
Entity File Number 001-42767  
Entity Registrant Name J-Star Holding Co., Ltd.  
Entity Central Index Key 0001875016  
Entity Incorporation, State or Country Code E9  
Entity Address, Address Line One 7F-1, No. 633, Sec. 2  
Entity Address, Address Line Two Taiwan Blvd  
Entity Address, Address Line Three Xitun District  
Entity Address, City or Town Taichung City  
Entity Address, Country TW  
Entity Address, Postal Zip Code 407  
Title of 12(b) Security Class A Ordinary Shares  
Trading Symbol YMAT  
Security Exchange Name NASDAQ  
Entity Well-known Seasoned Issuer No  
Entity Voluntary Filers No  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Non-accelerated Filer  
Entity Emerging Growth Company true  
Elected Not To Use the Extended Transition Period false  
Document Accounting Standard International Financial Reporting Standards  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   13,953,333
Entity Listing, Par Value Per Share $ 0.50  
ICFR Auditor Attestation Flag false  
Document Financial Statement Error Correction [Flag] false  
Auditor Opinion [Text Block] We have audited the accompanying consolidated balance sheets of J-star Holding Co., Ltd. and its subsidiaries (collectively the “Group”) as of December 31, 2025 and 2024 and the related consolidated statements of comprehensive (loss) income, changes in equity, and cash flows for each year in the three-year period ended December 31, 2025 and the related notes (collectively referred to as the “consolidated financial statements”). In our opinion, the consolidated financial statements present fairly, in all material respects, the financial position of the Group as of December 31, 2025 and 2024, and the results of its operations and its cash flows for each year in the three-year period ended December 31, 2025, in conformity with International Financial Reporting Standards as issued by the International Accounting Standards Board.  
Auditor Name WWC, P.C.  
Auditor Firm ID 1171  
Auditor Location San Mateo, California  
Business Contact [Member]    
Entity Addresses [Line Items]    
Entity Address, Address Line One 7F-1, No. 633, Sec. 2  
Entity Address, Address Line Two Taiwan Blvd  
Entity Address, Address Line Three Xitun District  
Entity Address, City or Town Taichung City  
Entity Address, Country TW  
Entity Address, Postal Zip Code 407  
City Area Code +886  
Local Phone Number 423229900  
Contact Personnel Name Mr. Jing-Bin Chiang