Annual report pursuant to Section 13 and 15(d)

Document And Entity Information

Document And Entity Information - USD ($)
12 Months Ended
Sep. 30, 2018
Dec. 17, 2018
Mar. 31, 2018
Document Information [Line Items]      
Document Type 10-K    
Amendment Flag false    
Document Period End Date Sep. 30, 2018    
Document Fiscal Year Focus 2018    
Document Fiscal Period Focus FY    
Entity Registrant Name Arch Therapeutics, Inc.    
Entity Central Index Key 0001537561    
Current Fiscal Year End Date --09-30    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Filer Category Non-accelerated Filer    
Entity Public Float     $ 42,000,000
Trading Symbol ARTH    
Entity Common Stock, Shares Outstanding   164,441,786  
Entity Shell Company false    
Entity Emerging Growth Company false    
Entity Small Business true