Annual report pursuant to Section 13 and 15(d)

Document And Entity Information

Document And Entity Information - USD ($)
12 Months Ended
Sep. 30, 2022
Dec. 28, 2022
Mar. 31, 2022
Document Information [Line Items]      
Entity Central Index Key 0001537561    
Amendment Flag false    
Current Fiscal Year End Date --09-30    
Document Fiscal Year Focus 2022    
Document Fiscal Period Focus FY    
Document Type 10-K    
Document Annual Report true    
Document Period End Date Sep. 30, 2022    
Document Transition Report false    
Entity File Number 000-54986    
Entity Registrant Name ARCH THERAPEUTICS, INC.    
Entity Incorporation, State or Country Code NV    
Entity Tax Identification Number 46-0524102    
Entity Address, Address Line One 235 Walnut Street, Suite 6    
Entity Address, City or Town Framingham    
Entity Address, State or Province MA    
Entity Address, Postal Zip Code 01702    
City Area Code 617    
Local Phone Number 431-2313    
Title of 12(g) Security Common Stock, par value $0.001 per share    
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 Small Business true    
Entity Emerging Growth Company false    
Entity Shell Company false    
Entity Public Float     $ 22,000,000
Entity Common Stock, Shares Outstanding   249,936,370  
Auditor Firm ID 23    
Auditor Name Baker Tilly US, LLP    
Auditor Location Tewksbury, Massachusetts