Document And Entity Information (USD $)	12 Months Ended
	Sep. 27, 2014	Oct. 23, 2014	Mar. 29, 2014
Document and Entity Information [Abstract]
Entity Registrant Name	INSTEEL INDUSTRIES INC
Document Type	10-K
Current Fiscal Year End Date	--09-27
Entity Common Stock, Shares Outstanding		18,377,251
Entity Public Float			$ 272,849,494
Amendment Flag	false
Entity Central Index Key	0000764401
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Well-known Seasoned Issuer	No
Document Period End Date	Sep. 27, 2014
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY